Category: 3. Business

Thin films with a high technical specification have many applications, including within lithium-ion batteries^1,2, solar panels³ and polymer electrolyte membrane fuel cells^4,5. Roll-to-roll slot die coating is a widely used technology for the industrial scale manufacture of thin films, which involves pumping a fluid through a slot in a metal block onto a moving substrate^4,6. The high line speed, high material utilization and ability to pre-select coating thickness are factors which have contributed to roll-to-roll slot die coating becoming ubiquitous in state-of-the-art thin film manufacture⁷.

Slot die coating has many adjustable process parameters, which influence the coating formed. These parameters, as illustrated in Fig. 1, include substrate velocity, coating gap, shim thickness and composition of coating solution^4,8. Slot die coating forms defect-free coatings using parameter sets within the operating window⁴. Outside of this window, the coating process is susceptible to significant defects such as ribbing, dripping and air entrapment. However, even when remaining within the operating window, different sets of coating parameters give different coating properties^9,10. The wet coating thickness, for example, can vary within the operating window depending on the ratio of pump rate to substrate velocity⁴. However, more subtle features such as coating uniformity and edge quality also depend on the process conditions used^10,11. Schmitt et al. termed regions within the operating window with a high coating uniformity, the quality window¹⁰.

Many theoretical models can predict the operating window for slot die coating such as those by Ruschak¹², Higgins and Scriven¹³ and Yamamura¹⁴. However, to the best of the authors’ knowledge, there is no efficient theoretical understanding or analytical models, of how process parameters affect features of the coating within the operating window. This is noteworthy as coating properties such as unexpected coating thickness deviations and coating uniformity have a large influence on the performance of subsequent devices¹⁵. For example, a high coating uniformity is essential for Li-ion battery electrodes as it minimizes rejection rate and has a large influence on the electrochemical performance of the electrode^1,16. As a specific example of this, Mohanty et al. found that non-uniform Li-ion NMC electrode coatings gave poor rate capability, especially at higher rates, and a lower Coulombic efficiency¹⁷. Coating uniformity is also an important coating feature for organic photovoltaic devices, with a higher uniformity resulting in improved device performance¹⁸.

Despite the dogma that slot die coating provides perfect thickness control, in reality small changes in the coating width can occur depending on the process parameters used, which in turn alters the coating thickness¹⁹. This effect is due to the non-Newtonian behavior of polymeric coating solutions²⁰. The coating’s thickness determines the energy density of a Li-ion battery, with a thinner than expected electrode giving a lower cell energy density²¹. Additionally, a thicker than expected electrode may lead to mass transport limiting charging/discharging rates. These differences in coating thickness are particularly significant for industrial operators in applications which utilize stripe coatings or with strict thickness requirements.

The lack of theoretical modeling and understanding of how input parameters impact these fundamental coating properties in slot die coating⁴ means that operators currently optimize production through iterative, trial and error adjustments^1,11. The large amount of process parameters and competing outputs exacerbate the complexity of this optimization and make trial and error unlikely to result in the coating process being truly optimized. This has cost implications, due to the waste material produced and production time lost during this laborious process. Additionally, this type of optimization leaves potential device performance improvements untapped.

Despite computer aided optimization having been implemented in a wide variety of manufacturing processes in other sectors, such as additive manufacturing^22,23 and pharmaceutical manufacturing²⁴, it is not routinely applied in industrial roll-to-roll slot die coating lines. Harnessing computer-aided optimization in this context could unlock significant cost and performance benefits for a wide range of devices. Furthermore, such an approach has the potential to provide valuable insights into the relationship between key coating parameters and the resultant properties of the coating.

The literature has documented some instances of computer-assisted optimization for roll-to-roll slot die coating^16,25,26. However, there are no reports linking fundamental process parameters to critical coating properties, highlighting a significant gap in the understanding of slot die coating within its operating window. Additionally, there has not been any utilization of a machine learning model to provide experimental improvements in coating features. This disconnect highlights a divide between the theoretical modeling and practical application, raising concerns about the effectiveness or applicability of the previously reported methods.

Machine learning-based surrogate optimization is well-suited for slot die coating, due to the process’s complexity and the numerous interacting inputs and outputs. Surrogate modeling involves constructing computationally efficient approximations of approximate complex, computationally expensive, or time-intensive simulations using experimental data and is well known for capturing intricate non-linear relationships^16,27. Surrogate models are particularly effective when analytical models are unavailable.

There are a range of analytical approaches and multivariate modeling tools that can be used for modeling industrial processes. For instance, multiple linear regression (MLR), polynomial regression (PR)²⁸, principal component analysis (PCA), latent variable model (LVM), orthogonal partial least squares (OPLS)²⁹, Gaussian process (GP), and Artificial Neural Networks (ANN)³⁰. Among these, Radial Basis Function Neural Networks (RBFNNs), are a notable machine learning modeling method due to their ability to accurately describe complex nonlinear relationships while maintaining computational efficiency. With its universal approximation capability³¹, RBFNNs excel at modeling complex systems with high accuracy and efficiently capturing local variations in data.

However, alternative surrogate modelling methodologies also warrant consideration. For example, Gaussian Process regression is widely recognized for its flexibility and ability to provide uncertainty estimates, making it a strong candidate for problems where quantifying prediction confidence is important. Similarly, Support Vector Regression, which adapts support vector machine methodology to regression tasks, is known for its robustness in high-dimensional spaces and often achieves good generalization on relatively small datasets³². Comparative studies have demonstrated that while RBFNNs typically offer fast training and effective local modelling, Gaussian Process models may outperform them in terms of predictive error under certain circumstances, particularly with small datasets or when uncertainty quantification is required. Furthermore, recent research has shown that SVR can deliver competitive performance, though its accuracy might be surpassed by RBFNNs and Gaussian Process models under some conditions, such as in delamination detection in composite laminates³³. Therefore, incorporating comparative analysis with these surrogate modelling techniques can further reinforce the strengths and appropriate use-cases for RBFNNs, highlighting the need for model selection based on the specific characteristics of the data and the modelling objectives.

Although gradient-based optimization techniques can effectively explore solution spaces, they have inherent limitations such as generalization challenges and a lack of performance guarantees. Surrogate-assisted evolutionary computation addresses these issues by using computationally efficient models to estimate fitness functions in evolutionary algorithms. This approach is particularly valuable for complex optimization problems with computationally expensive objective functions. By employing surrogate models like RBFNNs, this approach significantly reduces the need for costly experimental evaluations, accelerating both exploration and exploitation of the parameter space. Additionally, acquisition functions further balance exploration and exploitation, making this method particularly effective for high-dimensional optimization tasks.

Reference Vector Guided Evolutionary Algorithm (RVEA), a flexible and scalable meta-heuristic evolutionary optimization method³⁴, is well-suited for complex processes, that traditional multi-objective problem algorithms struggle with in terms of performance and diversity maintenance³⁵. RVEA utilizes a uniform distribution of reference vectors – directions in the input parameter space- to guide the search for optimal solutions. This method ensures a diverse set of solutions spread across the Pareto front, which represents the set of optimal trade-offs between conflicting objectives. Additionally, RVEA’s adaptive angle penalty mechanism dynamically adjusts selection pressure, maintaining a balance between convergence and diversity, making it well-suited for complex, high dimensional problems.

This article presents an experimentally validated optimization approach for roll-to-roll slot die coating, combining a RBFNN surrogate model with RVEA. The coating composition used resembles many industrially relevant coatings, such as slurries for lithium ion batteries and solar cells^1,36, making insights gained applicable across a wide range of fields. This article aims to promote the widespread implementation of machine learning-based optimization in roll-to-roll slot die coating, offering potential improvements in cost, performance and process understanding.

In our nationwide observational study, we found a significantly higher risk of in-hospital mortality in haemoadsorption patients compared to a matched control group, suggesting that the widespread use of this technique in COVID-19 is not justified. Of note, ECMO support and CPR were also associated with increased mortality as independent variables in the logistic regression model. However, we emphasise that while ECMO and CPR are essential interventions that replace or restore life-sustaining functions, haemoadsorption is an adjunctive therapy whose potential benefits and risks to the patient must be carefully weighed. The use of haemoadsorption therefore requires more nuanced medical and ethical considerations for application in clinical practice.

Few small and non-confirmatory RCTs from Germany have evaluated the use of haemoadsorption with the CytoSorb® device in critically ill COVID-19 patients^22,23,24. In patients with vasoplegic shock and renal replacement therapy (n = 49), 30-day mortality was not significantly improved by haemoadsorption (74% vs. 58% in the control group, p = 0.23). Neither effect on IL-6 levels, catecholamine requirement, nor other clinical endpoints was found in this study²⁴. The CYCOV trial included COVID-19 patients supported with VV-ECMO (n = 34) and revealed a significantly higher 30-day mortality in the haemoadsorption group (76% vs. 18% in the control group, p = 0.0016), however, mortality was assessed only as a secondary endpoint²³. Another RCT with COVID-19 patients failed to demonstrate a significant mortality benefit (n = 24; 28-day mortality 58% in the intervention group vs. 67% in the control group, p = 1.0). Of note, in this trial, increased IL-6 levels at or above 500 ng/L were among the inclusion criteria²². Despite a previous promising report of CytoSorb® therapy during VV-ECMO in COVID-19 patients (n = 8)¹⁸, no significant reduction of IL-6 plasma levels could be observed^23,24.

In our cohort, in-hospital mortality was significantly higher in patients who received haemoadsorption compared to those treated without. These findings confirm concerns regarding the safety of uncritical use of this technique in clinical routine for severely ill COVID-19 patients. Recent studies challenge the relevance of hypercytokinemia in critical COVID-19^14,15. A previous single-centre study shows significantly lower levels of IL-6, IL-8, and tumor necrosis factor (TNF) in patients with COVID-19-associated ARDS (n = 62) compared to septic shock patients with (n = 51) and without (n = 15) ARDS and a mixed picture when comparing COVID-19 to trauma (n = 62) and out-of-hospital cardiac arrest (n = 30)¹⁵. In a meta-analysis of multiple published cohorts, pooled mean IL-6 plasma levels for COVID-19 patients (n = 1,245) were significantly lower compared to other critical conditions, including chimeric antigen receptor (CAR)-T cell-induced cytokine release syndrome (100-fold difference, n = 72), hyperinflammatory ARDS (50-fold difference, n = 868), sepsis (30-fold difference, n = 5,320), and hypoinflammatory ARDS (5-fold difference, n = 1,899)¹⁴. A similar trend was observed for IL-8, TNF and other pro-inflammatory cytokines, while acute phase reactants were elevated, suggesting a hypoimmune state with virus-mediated tissue damage as the cause of critical COVID-19¹⁴. Based on these concerns and the findings from the above mentioned RCTs, the rationale and the safety for the routine use of haemoadsorption should be critically considered. We therefore suggest limiting the use of haemoadsorption in COVID-19 to carefully designed clinical trials.

Excessive release of cytokines is a hallmark of sepsis and ARDS independent from COVID-19¹⁴. Recent randomised evidence suggested that haemoadsorption may be useful as a therapeutic approach in sepsis and septic shock³¹. Based on the growing body of literature¹, we hypothesised that a septic shock may have been the indication for haemoadsorption in our study population rather than critical COVID-19. To account for the interdependency of haemoadsorption and septic shock, we introduced interaction variables in regression modelling. The results confirmed that there was no survival benefit from haemoadsorption in either the overall group or in patients with septic shock. Similarly, a retrospective propensity score matched analysis of septic patients with hypercytokinemia (n = 143; mean initial IL-6 levels of 58,000–60,000 ng/L) showed neither difference in IL-6 reduction, haemodynamic stabilisation, nor mortality for patients treated with haemoadsorption³². These findings suggest that the use of haemoadsorption requires more stringent patient selection criteria and is not necessarily justified for septic shock patients with COVID-19^3,5.

Our granular analysis delineates several critical factors related to mortality among patients receiving haemoadsorption that should be considered and further assessed in clinical trials. Advanced age and poor health, as assessed by the Elixhauser score, pose a high risk of death. Haemoadsorption did not provide a survival benefit for critically ill COVID-19 patients who required ECMO, CPR and/or dialysis. Of note, more than half of the CPR patients in our haemoadsorption cohort (54.3%, 108/199) received this treatment after IHCA. Previously, the use of haemoadsorption showed no benefits after extracorporeal CPR in a single-centre RCT (n = 41) and was associated with higher mortality for out-of-hospital cardiac arrest patients (n = 72) in a propensity-matched single-centre registry study^33,34. Due to inherent limitations, we cannot determine if the haemoadsorption treatment was related to CPR but nevertheless, our data do not suggest a positive impact of the haemoadsorption therapy on the mortality of COVID-19 patients at any time point after IHCA. While male sex is known to have a higher risk of COVID-19-related ICU admission and death^35,36, gender was matched and did not play a detrimental role in our study population. The deployment of haemoadsorption correlated with higher numbers of coagulopathies, cardiac arrhythmia, and CPR but with lower numbers of pulmonary embolism and stroke. At the same time, coagulation disorders were associated with an increased risk of death in the control group, which is consistent with numerous studies confirming the cardiovascular manifestations of COVID-19 and their poor prognosis for patients³⁷. The COVID-19 anticoagulation guidelines in Germany have been adjusted several times during the pandemic to balance the risk of thrombosis and haemorrhage³⁸. Within our study, the patient cohort experienced a spectrum of treatment regimens reflective of an iterative learning process in protocol development, which may have led to an elevated rate of cardiovascular mortality in the control group due to suboptimal anticoagulation targets. In contrast, haemoadsorption therapy was administered under consistent, manufacturer-recommended anticoagulation protocols, potentially attenuating the risk of fatal cardiovascular outcomes. Acute liver failure was detrimental to survival in both groups, although previous case studies on the use of haemoadsorption for this indication in non-COVID-19 patients were positive^39,40. Further, our data confirm a significant risk for cardiac arrhythmia associated with haemoadsorption therapy, which has also been reported in the RCT with vasoplegic shock patients (12 events in n = 10, 47.6% of patients in the haemoadsorption group vs. 3 events in n = 3, 11.5% patients in the control group, p = 0.0115)²⁴. Patients with malignant diseases had a significantly increased risk of death if they were treated with haemoadsorption, which calls for particular caution. Even though a causality cannot be established with the current evidence, the risk factors derived in our study, among others, must be closely monitored and reported in future studies involving haemoadsorption.

Early initiation of haemoadsorption has been suggested for the treatment of septic shock patients¹⁹. In the retrospective CTC registry-based study (n = 100), early (≤ 87 h) use of haemoadsorption was associated with a reduction of the duration of mechanical ventilation (7 [2–26] days in the early treatment group vs. 17 [7–37] days in the late treatment group, p = 0.02), less days of ECMO support (13 [8–24] vs. 29 [14–38] days, p = 0.021), and shorter ICU stays (17 [10–40] vs. 36 [19–55] days, p = 0.002)²⁰. However, no significant reduction of 90-day mortality was observed in the early treatment group (18%) compared to the late therapy start (34%)²⁰, and the study suffered from serious methodological shortcomings, most importantly the absence of a control group²¹. We did not observe a significant impact on survival by early versus late therapy initiation in the multiple logistic regression model with a spline function controlling for therapy timing. Of note, our haemoadsorption group cannot be directly compared with the CTC patients, as our dataset does neither include laboratory values, respiratory parameters, nor the sequential organ failure assessment (SOFA) score, which are not included in the DESTATIS datasets. Nevertheless, 90-day mortality was remarkably lower among the retrospectively selected haemoadsorption patients on VV-ECMO support from the CTC registry (26%) than the in-hospital mortality in German ICUs (n = 357, 81% of all 443 VV-ECMO patients treated with haemoadsorption), suggesting a highly selected patient cohort in the CTC registry limiting the generalisability of the results. Still, the timing of COVID-19 treatment is crucial for immunomodulatory approaches like e.g. the widely accepted anti-IL-6 antibody tocilizumab⁴¹, and needs to be carefully evaluated also for haemoadsorption.

COVID-19 was shown to manipulate numerous biological pathways and cause a highly individual immune response^42,43. Attempts to characterise the specificity of the CytoSorb® haemoadsorption device in septic and cardio-operative patients showed very different specificity profiles and demonstrated in some patients the elimination of apolipoprotein A1, serotransferrin, α-1-antitrypsin, immunoglobulins, and other proteins that are key in numerous biological pathways⁴⁴. Many of these proteins are not quantified in routine clinical practice, making it difficult to understand their role for patient outcomes. It is therefore reasonable to assume that the non-specific and still undefined removal of biomolecules from the blood may have adverse effects that could reduce or eliminate the benefits of haemoadsorption in some patient groups. For example, longitudinal biomarker profiling of ECMO patients with and without haemoadsorption (n = 22) revealed a reduction of IL-10, that was speculated to exacerbate COVID-19-induced organ damage⁸. Further, clinicians must consider that haemoadsorption has been reported to adsorb various drugs and their active intermediates in vitro and in vivo⁹. Given the advanced age and poor health of non-surviving haemoadsorption patients, the removal of critical drugs such as immunosuppressants, antiepileptics, antiinfectives, and anticoagulants from the patients’ blood can be fatal.

Limitations

This observational study has limitations. The analyses were conducted with retrospective data, which were provided by the Federal Statistical Office. Due to the institutionally ensured anonymity, no conclusions can be drawn at individual patient level. Even if the sequence of events or treatment indications cannot be determined, we can confirm independent risk factors for mortality by regression modelling. We cannot provide laboratory data on inflammatory marker profiles or essential concomitant medication since they are in most cases not coded for reimbursement. Individual clinical parameters such as oxygen indices or the clinical presence of ARDS were not included in the matching process, as these variables are not coded for reimbursement and are therefore not available in the data set. Likewise, the reconstruction of clinical scoring systems (such as APACHE II or SOFA) using remuneration data alone is methodologically limited. To avoid misinterpretation suggesting the inclusion of clinical parameters (e.g. lab values or blood gas analyses), these metrics were not reported. This represents a limitation with regard to comparability with other studies that include detailed clinical parameters. Long-term survival analysis be conducted based on this dataset. In contrast, the Elixhauser Score a validated measure of disease severity derivable from remuneration records and is validated for hospitalised patients^25,45. A possible coding-related bias in the Elixhauser score would affect all patient groups in our analysis equally. Furthermore, we assume that any facility-specific bias in our analysis is largely averaged out by the large number of hospitals (204 ICUs) covered in a short period of time. Our analysis does not provide indications and medical rationales for the use of haemoadsorption (e.g. myoglobin removal during rhabdomyolysis)⁴⁶. Further, we cannot evaluate the physician’s assessment of the patient’s state. Specifically in our extremely vulnerable study group, the physician’s decision to use a costly and disputable therapeutic approach may have led to a bias in the selection of those patients who appeared to have the best chance of survival. Notably, the OPS codes for multiple haemoadsorption devices and no conclusion can be drawn regarding the differences in the devices from different manufacturers.

Introduction

In recent years, natural copolymers have attracted widespread attention due to their diverse applications. These polymers can be obtained from microorganisms, plants, and animals, such as some naturally occurring anionic heteropolysaccharides.¹ Especially, polysaccharides are widely utilized in drug delivery, tissue engineering, and biosensors due to their biocompatibility, abundance and well-established modification.^2,3 Chondroitin sulfate (CS), a naturally derived polysaccharide, exhibits excellent biocompatibility, remarkable biostability and protein adsorption capacity. It has been extensively utilized in various biomedical fields.⁴ CS can be biosynthesized with varying disaccharide compositions and carbohydrate backbones, resulting in different positions of sulfate groups.⁵ It is composed of alternating copolymer of (β-1, 3)-linked glucuronic acid and (β-1,4)-N-acetyl galactosamine.⁶ Based on the number and positions of sulfate groups, CS is classified into different isomers, including chondroitin sulfate A (CSA), chondroitin sulfate B (CSB), chondroitin sulfate C (CSC), chondroitin sulfate D (CSD), and chondroitin sulfate E (CSE).⁷ CSA and CSC are respectively composed of disaccharides sulfated at the C4 or C6 position of the GalNAc residue. The structure of CS varies across species and tissues, exhibiting different levels of disulfated disaccharides. These include the disaccharide with sulfate groups at position C2 of GlcA and C6 of GalNAc (CSD), at positions C4 and C6 of the GalNAc unit (CSE), or at C2 of GlcA and C4 of GalNAc (CSB).⁵

Sulfation patterns are crucial to the biological activity of CS, influencing its interactions with proteins and its roles in cell signaling, tissue development and maintenance. The negatively charged sulfate groups facilitate binding to positively charged regions of proteins, thereby modulating biological activity and tissue-specific functions.⁸ For instance, the high density of negative charges on the surface of CS enables interactions with positively charged components of the immune system. These interactions can modulate immune cell activity and influence the release of inflammatory mediators. Thus, CS contributes to the maintenance of tissue homeostasis and resolution of inflammatory processes by regulating inflammation.⁹ Additionally, CS can exert a targeting function through electrostatic interactions. It is readily recognized by the CD44 receptor, which is highly expressed on chondrocytes and tumor cells, and forms a stable hydrogen bonding network with basic amino acid residues (such as lysine and arginine) on the CD44 receptor surface via electrostatic forces. This interaction promotes receptor-mediated endocytosis, enhancing targeting efficiency.¹⁰

CS is present on the cell surface and within the extracellular matrix (ECM), and is covalently bound to proteins to form proteoglycans.^11,12 CS itself has anti-inflammatory and anti-osteoarthritic activities, and has become a dietary supplement approved by the United States and Europe.¹³ This polysaccharide is increasingly attracting attention as a component for providing stealth functions, improving interactions with target tissues, or achieving environmentally responsive drug release in the development of functional nanomedicines.¹⁴ CS is characterized by a series of physicochemical properties that make it a versatile material across various scientific fields. These properties include low immunogenicity, good biodegradability and water solubility.¹⁵

In the biomedical fields, nanoplatforms denote engineered nanostructured systems designed for integrated diagnosis and treatment. Nanoparticles (NPs) have the ability to encapsulate and deliver biochemical signals or drugs, and enhance their bioavailability.^16–18 NPs are considered promising carriers for drugs and imaging agents due to their ability to accumulate in therapy sites. Chaurasia et al developed novel macrophage-targeted doxorubicin (DOX)-loaded nanocapsules (NCAPs) using chondroitin sulfate (CS). These CS-anchored NCAPs were prepared with soybean oil core templates for complementary immunotherapy combined with chemotherapy in the treatment of leishmaniasis.¹⁹ The drug delivery efficiency of traditional nanomaterials is still low, resulting in drug distribution in non-target tissues and subsequent toxic effects.²⁰ Furthermore, passive tumor targeting is achieved through enhanced penetration and retention effects.²¹ Notably, active targeting strategies can enhance drug delivery efficiency.^22,23 CS-based nanoplatforms exhibit excellent biocompatibility, specific targeting ability to CD44 receptors, and versatile functionality for diverse biomedical applications. CS offers distinct advantages over other polysaccharide-based carriers. For instance, hyaluronic acid is susceptible to degradation by hyaluronidase.²⁴ This limitation can compromise targeting specificity and therapeutic efficacy. In contrast, CS demonstrates greater resistance to hyaluronidase degradation and has the ability to target both CD44 and E-selectin, enhancing its potential as a stable and effective drug delivery platform. Additionally, CS-based nanoplatforms address two major challenges faced by conventional nanocarriers: poor in vivo stability and limited tissue penetration due to physiological and microenvironmental barriers. Traditional NPs are prone to aggregation and reduced circulation time in response to fluctuations in ionic strength or pH within the physiological environment.²⁵ The polyanionic surface of CS minimizes serum protein adsorption and macrophage-mediated phagocytosis, thereby prolonging the drug’s half-life and enhancing in vivo stability. This stability is further reinforced by electrostatic repulsion, which prevents particle aggregation.²⁶ Among various treatment strategies, multifunctional nanoplatforms have gained significant attention for their potential in disease therapy, offering combined capabilities such as targeted drug delivery, diagnostic imaging, and controlled therapeutic release.²⁷ Therefore, the development of suitable nanoplatforms for disease treatment requires a balanced approach. Prioritizing therapeutic efficacy alone while overlooking potential side effects can hinder clinical translation. For successful clinical application, both safety and effectiveness must be carefully considered and optimized.²⁸

Currently, the primary methods for drug loading into NPs are as follows: emulsion-solvent evaporation, covalent conjugation, dialysis, nanoprecipitation, thin-film dispersion, supercritical fluid technology, spray drying, electrospinning, ionotropic gelation, and microfluidics. However, among these existing nanoparticle drug-loading techniques, emulsion-solvent evaporation, covalent conjugation, drug nanocrystal encapsulation, dialysis and electrostatic adsorption have shown greater applicability in CS- based nanoplatforms.^29–32 These techniques are well-suited due to the unique chemical and physical properties of CS.

CS-based formulations or composite materials have been previously summarized.^33,34 The present review highlights the recent research advancements in CS-based nanoplatforms for biomedical applications. These nanoplatforms have demonstrated remarkable potential in tumor therapy and disease treatment, particularly in anti-inflammation, owing to their distinctive physicochemical properties and biological functions. Additionally, CS-based nanoplatforms have application prospects in tissue engineering and biosensing. Finally, this review explores the challenges, difficulties, and future opportunities associated with CS nanoplatforms.

CS-Based Nanoplatform in Tumor Therapy

Conventional cancer treatments, such as chemotherapy and radiotherapy, exhibited moderate efficacy in suppressing tumor progression. However, these therapies imposed significant physical and psychological burdens on patients.³⁵ Despite considerable advances in diagnostic precision and treatment strategies, cancer remains a major global health challenge. Continuous innovation in treatment approaches is essential to overcome evolving therapeutic resistance and disease heterogeneity. NPs demonstrate substantial potential as drug carriers among the various emerging cancer therapeutic strategies. These NPs have proven to be promising carriers for both therapeutic drugs and imaging agents, as they can effectively target and accumulate in solid tumors.³⁶ The enhanced permeability and retention (EPR) effect is based on the defects of tumor vasculature and poor lymphatic drainage, which allows NPs to extravasate and accumulate in tumors.³⁷ The targeting specificity and retention time of NPs can be enhanced by the surface modification of nanomaterials, which is critical for tumor therapy. Currently, many nanocarriers are designed for the co-delivery of various drugs, including small chemical molecules, nucleic acids and proteins.^38,39 Small chemical molecules, such as DOX, paclitaxel (PTX) and methotrexate, are conjugated to amphiphilic polymers using chemically sensitive bonds, leading to the creation of micelles and vesicles capable of encapsulating both hydrophobic and hydrophilic drugs.⁴⁰ These formulations exhibited synergistic effects on tumor cells. Furthermore, in combination with nucleic acids, such as plasmid DNA, small interfering RNA and microRNA, small molecular chemical drugs can be co-delivered using cationic amphiphilic polymers to synergistically target and eradicate tumor cells.⁴⁰

CS exhibits unique characteristics that make it a promising vehicle for cancer therapy. Studies have shown that the expression levels of CD44 receptors are markedly elevated in some tumor cells and their metastases compared to normal cells.⁴¹ CS has been proven to target the highly expressed CD44 receptors with high specificity.⁴² As a carrier molecule, CS can be conjugated either covalently or non-covalently with drugs or functional molecules, thereby endowing these conjugates with targeted functionality.^43–45 These resulting copolymer-based NPs exhibited high specificity and reduced biological toxicity.³⁶ These conjugations of functional substances with CS vary in terms of binding mechanisms and composition, leading to a diverse range of formulations, including polymeric micelles, nanogels and CS-conjugated drug NPs.^29,46–48 Various CS-decorated nanostructures, such as dendritic macromolecules and lipid-based NPs, have been identified.^49,50 These nanoplatforms hold significant potential for tumor treatment.

Polymeric Micelles

Polymeric micelles are nanoscale structures formed by the self-assembly of amphiphilic copolymers, and have been extensively used in tumor therapy.⁵¹ Hydrophilic CS can be chemically linked to a hydrophobic polymer, yielding an amphiphilic copolymer analogous to a surfactant. Upon reaching the critical micelle concentration, the amphiphilic polymer can spontaneously form polymer micelles in an aqueous medium, forming a well-defined core-shell architecture. The hydrophobic segments aggregate to constitute the inner core, while the hydrophilic CS chains protrude outward to form the aqueous-facing shell. Further, hydrophobic drugs could be encapsulated into the core of these self-assembled micelles (Table 1). This form has been shown to enhance the solubility of target drugs and concomitantly increase their stability within the internal tumor environment through the steric hindrance effect.⁵² Polymeric micelles have been demonstrated to prolong the duration of drug circulation, reduce clearance rate, increase half-life and enhance the biodistribution of anticancer drugs.⁵³ CS and deoxycholic acid (DOCA) were successfully conjugated through adipic dihydrazide (ADH)-mediated amidation, forming a promising drug carrier CS-DOCA. By adjusting the degree of substitution of DOCA, the drug loading and release rate can be greatly influenced. As the degree of substitution increased, the cellular uptake and cytotoxicity of the self-assembled NPs were increased in MCF-7 cells.⁵⁴ Wu et al prepared CS-DOX to encapsulate berberine (BBR). This co-delivery system equipped with DOX and BBR could effectively inhibit breast cancer growth and metastasis.¹⁵ Gaber et al co-encapsulated etoposide and all-trans RA within amphiphilic zein-CS copolymeric micelles, demonstrating an effective dual-drug delivery platform for breast cancer targeted therapy.⁵⁵

Table 1 Application of CS-Based Polymeric Micelles in Tumor Therapy

In addition to the passive EPR effect, polymer micelles modified with targeted substances on their surface can specifically bind tumor cells, thereby achieving active targeting.^74,75 CS-based polymeric micelles target the CD44 receptors on cancer cells.^76,77 For example, Yu et al prepared CS-based NPs (CS-His), which can target the tumor cells and improve the efficiency in killing the HepG2 cell line.⁵⁶ Luo et al developed a dual-drug delivery system by co-encapsulating retinoic acid (RA) and DOX into CS-DOCA NPs. The engineered NPs demonstrated hepatic-targeting capability and destroyed the Golgi apparatus, which has great potential for the treatment of liver cancer.⁵⁷ Elhasany et al developed zein-CS NPs that integrate superparamagnetic iron oxide NPs for magnetic targeting and CS-mediated CD44 receptor targeting. This nanoplatform simultaneously encapsulated celastrol and sulfasalazine, demonstrating dual functionality for cancer theranostics through combined therapeutic intervention and diagnostic imaging capabilities.⁵⁸

Precise spatiotemporal drug release from the carrier is crucial for the development of the delivery system. There is an urgent need for intelligent NPs that can achieve specific local delivery and respond to the tumor microenvironment. These NPs should be based on active targeting and environmental responsiveness, ensuring site-specific drug release and safety.⁴² Environmentally responsive NPs, including pH, reactive oxygen species (ROS), redox and enzymatic triggers, can release drugs under specific conditions, which help to enhance the efficacy of targeted cancer therapy.^59,78–81

Thioketals (TK), diselenides, thioethers, aryl boronic esters and aminoacrylates are widely employed in the fabrication of ROS-responsive NPs. For example, Yu et al developed CSA-TK-CHS polymeric micelles by utilizing a ROS-cleavable TK linkage to conjugate CSA with cholesterol hemisuccinate (CHS). DOX encapsulated within these NPs demonstrated significantly enhanced release efficacy under elevated ROS levels. In vitro studies revealed that CSA-TK-CHS/DOX micelles exhibited markedly higher cytotoxicity in 4T1 and CT26 cells compared to free DOX. In vivo evaluations further demonstrated robust efficacy in suppressing tumor growth in 4T1 tumor-bearing mice.⁵⁹ Jeong et al prepared DOX-loaded CS-anthocyanin (ATC) nanocomplexes, which led to the fragmentation of the nanostructures in the presence of ROS. It was shown that CS-ATC-DOX significantly inhibited tumor growth due to the presence of ATC compared to CS-DOX.⁶⁰

Dithiomaleimide (DTM) and disulfide bonds are used in the fabrication of redox-responsive NPs. Disulfide bonds are typically formed through the oxidation of two sulfhydryl groups without the involvement of a maleimide group. The synthesis of disulfide bonds is simplified, leading to their widespread use in the redox-responsive polymeric micelles.⁸² Reduction-sensitive NPs utilizing disulfide bonds maintain stability during blood circulation, while enabling rapid degradation through sulfhydryl-disulfide exchange reactions within reducing microenvironments. This unique property has positioned them as a research hotspot for controlled drug release in tumor cells.⁸³ Tumors have a highly glutathione (GSH)-rich reducing environment, causing redox nanocarriers to decompose rapidly and enhance drug release. For example, Zhang et al used a chemical method to conjugate hydrophobic cabazitaxel (CTX) with CS through DTM, forming an amphiphilic redox-responsive nanosystem. After the dasatinib-loaded CS-DTM-CTX (CDC) was internalized by the tumor cells, the disulfide bonds were broken under the redox conditions of the tumor, accelerating the release of the drug. This disrupts the interaction between fibroblasts and cancer cells, effectively inhibiting tumor growth and metastasis.⁶¹ Wang et al employed disulfide linkages to covalently couple hydrophobic poly (lactic-co-glycolic acid) (PLGA) with CSA, fabricating a redox-responsive CS-based nanosystem. PLGA-ss-CSA loaded with DOX was released more efficiently in the presence of GSH than in the absence of GSH. Therefore, the NPs were an effective carrier for inhibiting A549 cells.⁶² Cai et al used disulfide bonds as linkages and designed redox micelles (CSA-ss-α-tocopherol succinate) for DOX delivery. Compared with non-responsive micelles, DOX-loaded responsive micelles had higher cytotoxic activity on A549 and AGS cells.⁶³ The redox-responsive nanocarriers have shown significant therapeutic advantages in tumor microenvironments with elevated GSH concentrations. Liu et al successfully encapsulated DTX into CS-ss-DOCA conjugate, developing dual redox/enzyme-responsive nanocarriers for the treatment of melanoma.⁶⁴ Yu et al designed CSA and AS1411 aptamer-mediated stimuli-responsive dual-targeting drug delivery systems (AS1411 aptamer-CSA-ss-DOCA) to suppress breast cancer metastasis.⁶⁵ Yu et al synthesized a targeted peptide (CDVEWVDVS)-modified CSA-ss-DOCA copolymer, which enabled DOX delivery for enhanced triple-negative breast cancer therapy.⁶⁶

Ester and carbonate bonds are extensively utilized in the field of pH-responsive nanoparticle research. Their primary mechanisms of action involve serving as connecting links in carriers or forming specific chemical bonds in prodrugs, enabling pH-responsive release within the acidic microenvironment of tumors. Relevant studies have indicated that pH-dependent NPs also play a distinctive role in tumor therapy. Azimijou et al prepared CS-cholesterol nanoassemblies with carbonate ester bonds and tunable hydrophobic contents.⁴ The characteristics of these bonds confer pH responsiveness of the CS-cholesterol NPs. Under acidic pH conditions, the conjugates rapidly decompose and release DOX for targeted drug delivery in the treatment of breast cancer. In vitro cytotoxicity assays demonstrated that DOX-loaded NPs had concentration-dependent anti-proliferative activity against 4T1, MCF-7 and MDA-MB-231 breast cancer cells. In comparison with free DOX, the NPs have been shown to enhance early apoptosis, improve cellular uptake, and better prevent tumor cell proliferation. Additionally, Zhang et al introduced weakly acidic carboxyl groups (-COOH) during the synthesis of CS-b-PLGA, endowing the resultant NPs with pH-responsive properties.⁶⁷

It is crucial to consider both the characteristics of the linking moieties and the inherent properties of the chemical bonds. For example, the unique charge properties of histidine (His) lead to the disassembly of micelles under acidic conditions, enabling the pH-responsive behavior of CS-His NPs.⁶⁸ The CS-His micelles encapsulated with docetaxel (DTX) could effectively kill QBC939 cells and improve the therapeutic effects on cholangiocarcinoma.⁶⁹ The tumor microenvironment exhibits elevated intracellular GSH and acidic pH levels. The design of stimuli-responsive drug delivery systems capable of sensing acidic conditions to enhance drug release within tumor regions represents a critical direction for future pharmaceutical research. This strategic approach holds significant potential for improving therapeutic precision while minimizing systemic toxicity through microenvironment-triggered activation mechanisms.

The intricate nature of the tumor milieu and the existence of multiple mechanisms necessitate the consideration of a multitude of factors in tumor therapy.⁸⁴ A single responsive mechanism or therapeutic modality remains challenging in achieving optimal therapeutic effects. Hence, integrating multiple strategies has been a key direction in the design of multi-responsive or multifunctional therapeutic systems. Yu et al have demonstrated that the integration of DOX into the CSA-ss-chlorin e6 (Ce6) delivery system enabled a combined chemo-photodynamic therapeutic strategy for triple-negative breast cancer, and significantly enhanced tumor suppression efficacy through synergistic effects.⁷⁰ Photodynamic therapy exhibited suboptimal therapeutic outcomes in the deep tumors due to the restricted penetration of laser light. Zhang et al developed the CS-Rh-LA graft by conjugating rhein (Rh) and lipoic acid (LA) to CS. DTX was effectively encapsulated into CS-Rh-LA nanoplatform, resulting in the tumor-specific drug release and structural stability during systemic circulation. This experimental evidence indicated the potential of Rh in synergizing with chemotherapeutic agents under ultrasound irradiation for sonodynamic therapy (SDT) against lung cancer (Figure 1).⁷¹

Figure 1 The synthesis of DTX/C-NPs and intravenous injection into mice through the synergistic effect of chemo-sonodynamic therapy to achieve the treatment of lung cancer. Adapted from Zhang Y, Khan AR, Yang X, et al. A sonosensitiser-based polymeric nanoplatform for chemo-sonodynamic combination therapy of lung cancer. J Nanobiotechnol. 2021;19:57. http://creativecommons.org/licenses/by/4.0/.71

Conventional chemotherapeutic agents lack specificity for cancer cells and thus have toxic effects on normal cells. The development of drug resistance in tumor cells during treatment is a major challenge. A drug efflux process facilitated by P-glycoprotein on the cell membrane, which induces drug resistance in tumor cells, is a key factor that needs to be addressed. NPs with P-glycoprotein inhibitors, such as apatinib (Apa) and quercetin (QT), is regarded as an effective strategy to overcome tumor resistance.^85,86 Wei et al utilized the hydrophobic interactions to co-encapsulate Apa and DOX into amphiphilic acetylated-CS-PpLX (ACP) micelles. The ACP-DOX+Apa micelles generate ROS upon laser irradiation, leading to the disintegration of micelles. Apa has been released to inhibit P-glycoprotein, thereby increasing DOX accumulation in MCF-7/ADR cells. Concurrently, the ROS from photodynamic therapy (PDT) triggered mitochondria-dependent apoptosis, enhancing the synergistic effects between Apa-induced DOX sensitivity and ROS-mediated PDT.⁷² Shi et al reported that PTX was encapsulated into CS-cys-QT/Ce6. With the help of QT, the anti-cancer efficiency of PTX against multidrug-resistant MCF-7 cells was enhanced. Under the laser irradiation, ROS was produced to promote the apoptosis of the cells.⁷³ Therefore, the combination therapy of chemotherapy-PDT is expected to become an effective way to overcome tumor resistance and improve the antitumor efficacy.

Nanogels

Nanogels exhibit various properties of NPs and hydrogels.^87,88 Nanogel is a three-dimensional structure that is cross-linked by physical or chemical means.⁸⁹ However, the main difference between nanogels and hydrogels is their size.⁹⁰ The minute size of nanogels facilitates effective penetration through biological barriers.^87,91 Nanogels exhibit exceptional versatility in drug delivery, capable of encapsulating both hydrophilic and hydrophobic therapeutic agents. Their three-dimensional network structure acts as a protective matrix, shielding loaded drugs from aggregation, denaturation and enzymatic degradation. Notably, the soft and deformable architecture of nanogels enables efficient transport through intercellular gaps or uptake via cellular endocytosis.^92–94 This unique property overcomes physiological barriers such as the extracellular matrix and epithelial tight junctions, facilitating enhanced tissue penetration and intracellular delivery. Moreover, their gel-like consistency enables adaptive deformation under mechanical stress, allowing passage through narrow capillaries and improving targeting efficiency to pathological sites. Nevertheless, studies on CS-based nanogels remain relatively limited in the antitumor applications.

Campea et al encapsulated SNP-CHO NPs within disulfide-crosslinked CS-based nanogels. In vitro studies revealed that the DOX-loaded CS-SH@SNP-CHO nanogels could release the drug with accelerated kinetics in a highly disulfide-reducing environment. In vivo experiments showed that the small-sized drug-loaded SNPs allowed for deeper drug penetration into poorly vascularized tumor cores compared to free DOX. With increasing concentrations of loaded DOX, the nanoassembly exhibits better CT26 cancer cell toxicity than SNP-CHO NPs. The nano-assemblies exhibited lower nonspecific tumor toxicity and greater therapeutic potential for treating larger tumors while avoiding the mild cardiac tissue toxicity associated with free DOX (Figure 2).⁹⁵ Setayesh et al showed that CS-octadecylamine conjugates could self-assembly to deliver curcumin and be effectively taken up by MCF-7 cancer cells.⁹⁶ Therefore, these nanogels hold promise for the effective inhibition of cancer cells.

Figure 2 SNP-CHO NPs are encapsulated in disulfide-bonded cross-linked CS-based nanogels for chemotherapeutic drug delivery. Adapted with permission from Campea MA, Lofts A, Xu F, et al. Disulfide-cross-linked nanogel-based nanoassemblies for chemotherapeutic drug delivery. ACS Appl Mater Interfaces. 2023;15:25324–25338. Copyright 2023 American Chemical Society.95 Abbreviations: CS-SH, disulfide-crosslinked thiolated chondroitin sulfate-based nanogels; SNP, Starch NPs; SNP-CHO, acterization of aldehyde-functionalized SNPs. Adapted from previous report (Reference 95).

The use of nanogels in combination with other components or therapeutic approaches, especially encapsulated in hydrogels, has been an effective strategy. Gil et al investigated an injectable hydrogel incorporating CS-nanogels loaded with cisplatin. The nanogels were synthesized through a metal-chelator coordination crosslinking method and subsequently integrated into a pH/temperature-dual responsive polyethylene glycol-poly (amino ester urethane) hydrogel matrix to accomplish tumor-targeted cisplatin delivery.⁹⁷ This structure involved the combination of a small molecule drug with an organic polymer material to achieve a specific drug delivery and therapeutic effect. Through this combination, the stability of the drug can be enhanced. The release rate can be controlled, and the interactions with specific cell types have been strengthened.

CS-Conjugated Drug NPs

Polymer-conjugated drug NPs are macromolecular structures in which the polymer is covalently bound to one or more therapeutic agents with pharmacological activity.⁹⁸ CS-drug NPs exhibited distinctive physicochemical properties and tumor-targeting capabilities. Unlike traditional physical encapsulation methods, CS-drug conjugates emphasize the direct chemical bonding of drugs to CS. These NPs achieve drug loading through covalent coupling, forming stable molecular conjugates rather than relying on physical entrapment within a carrier matrix. This type of nanoparticle also exhibits spontaneous self-assembly, producing amphiphilic polymers with hydrophobic drugs on the inside and hydrophilic CS on the outside. The structure of the NPs is more stable due to the involvement of chemical bonds. Compared to the simple encapsulation of drugs into the nanocarriers, the polymer-drug conjugates significantly enhanced drug loading capacity via covalent conjugation chemistry.⁹⁹ Xie et al reported that CSA-DOX NPs showed a significant increase uptake in A549 cells compared to free DOX. Further, the NPs can be a potential therapeutic platform for the lung cancer treatment.²⁹ Liu et al described that the CS-DOX-PLGA obtained after modifying CS-DOX with PLGA was more accessible to A549 cells. The NPs demonstrated reduced cardiotoxicity and maintained comparable antitumor efficacy through enhanced tumor-targeted drug delivery.¹⁰⁰ Liu et al designed the CS-ADH-Ce6-LA to produce potent therapeutic and anti-metastatic effects on melanoma in a combined chemo-acoustic kinetic manner.¹⁰¹ Li et al conjugated the photosensitizer Ce6 and RA to CS, thereby delivering two therapeutic agents. The Ce6-CS-RA NPs induced Golgi apparatus disruption and enhanced PDT efficacy against melanoma (Figure 3).¹⁰² Wang et al reported the development of self-assembled micelles derived from a chondroitin sulfate-cinnamaldehyde-curcumin-triphenylphosphine (CS-CA-CUR-TPP, abbreviated as CCCT) conjugate. The CCCT NPs were efficiently enriched and internalized by A549 cancer cells. Moreover, CCCT effectively inhibited tumor growth and helped overcome apoptosis resistance in cancer therapy.¹⁰³

Figure 3 Golgi apparatus-targeted prodrug Ce6-CS-RA NPs in vivo application for enhanced photodynamic immunotherapy. Reprinted from Acta Biomaterialia, 146, Haohuan Li, Caifeng Deng, Yulu Tan, Jianxia Dong, Yuanhao Zhao, Xiaorong Wang, Xingyue Yang, Jingwen Luo, Huile Gao, Yuan Huang, Zhi-Rong Zhang, Tao Gong, Chondroitin sulfate-based prodrug nanoparticles enhance photodynamic immunotherapy via Golgi apparatus targeting, 357-369, Copyright 2022, with permission from Elsevier.102 Abbreviations: Ce6, chlorin e6; RA, retinoic acid. Adapted from previous report (Reference 102).

It also has intelligent stimulus-responsive drug release mediated by pH-cleavable bonds and GSH-sensitive disulfide bonds.¹⁰⁴ This nanoplatform has been shown to enhance the therapeutic efficiency of the administered drug while reducing its distribution within normal tissues. Onishi et al investigated the potential of a novel nanomedicine, a combination of DOX and adipic acid dihydrazide-CS (CS-ACH), to enhance the efficacy of the drug under acidic conditions. In vitro experiments showed that CS-ACH-DOX resulted in accelerated drug release under acidic conditions. However, the therapeutic effect was not as pronounced as that of the free drug. In vivo experiments demonstrated that CS-ACH-DOX exhibited enhanced efficacy in the acidic tumor environment compared with free DOX. These results inferred that the nanodrug carrier has the potential to serve as a promising therapeutic agent.⁴³ Hu et al developed CS-based NPs, designated as the CS-ss-IR806 conjugate, for prostate cancer (PCa) therapy. The incorporation of disulfide bonds within the polymeric NPs conferred redox-responsive properties. In the presence of the photosensitizer IR806, the NPs demonstrated synergistic capabilities with SDT and PDT, thereby achieving superior therapeutic efficacy against localized PCa.¹⁰⁵ Li et al reported that Cys-DTX was encapsulated into CS-ss-DTX NPs, and Cys-DTX/CS-ss-DTX NPs were formed by self-assembly. These NPs exhibited redox-responsive release of DTX as well as high permeability and cytotoxicity in tumor tissues.¹⁰⁶ As previously reported, CS was conjugated with dasatinib (DAS) via the cathepsin B responsive GFLG peptide linker to form CS-GFLG-DAS (CGD). The resulting CGD NPs were capable of reversing the phenotype of cancer-associated fibroblasts and modulating extracellular matrix biosynthesis, thereby enhancing the therapeutic efficacy of anti-PD-1 treatment in 4T1 tumor-bearing mice.¹⁰⁷ Notably, Poursani et al developed esterase-responsive CS-chlorambucil (Chl) prodrugs and redox-responsive CS-LA conjugates, which were fabricated into enzyme- and redox-responsive NPs via a water/solvent evaporation technique. Subsequently, DOX was encapsulated within these NPs, constituting the first stimuli-responsive NPs. These NPs demonstrated triggered release of Chl and DOX into MDA-MB-231 cells in response to specific biochemical stimuli. The dual-responsive co-release system for multiple anticancer drugs synergistically enhanced cellular internalization and markedly improved antitumor efficacy.⁸⁰ This approach significantly improved the efficacy compared to the NPs co-loaded with a single drug and a single responsive modality. Consequently, these NPs were anticipated to serve as a highly effective treatment for aggressive solid cancers, particularly triple-negative breast cancer. Therefore, CS-conjugated prodrug NPs had a high drug-loading capacity and microenvironment-responsiveness at the tumor site.

CS-Coated NPs

CS is not only used as a synthetic drug carrier but also as an excipient for the coating of other carriers.¹⁴ Lipid nanoparticles (LNPs) have emerged as drug delivery vehicles in contemporary pharmaceutical research, particularly for lipophilic therapeutic agents such as paclitaxel, vincristine, and DTX.^108,109 However, the clinical translation of these nanocarriers faces critical barriers including low encapsulation efficiency for small molecule drugs, cytotoxicity induced by cationic lipids, and systemic toxicity resulting from liver penetration.^110–112 These issues not only affect the drug-loading capacity of NPs but also limit their safety and efficacy in vivo. CS and its derivatives have been demonstrated to protect NPs from premature clearance during circulation. CS-coated NPs achieve prolonged circulation via steric stabilization and facilitate efficient intracellular drug delivery, while the NPs could achieve ligand-receptor binding specificity by active targeting.^113,114 Therefore, CS coating emerges as a viable strategy to mitigate cationophore toxicity. By integrating steric stabilization, active targeting and toxicity mitigation, CS-coated NPs offer a multifunctional platform for advanced drug delivery. For example, Liang et al employed the CS derivative (CS-oleic acid) to encapsulate DOX nanocrystals. This approach showed the drug targeting and responsiveness to the internal environment of the tumor.⁴⁴ It also exhibited superior therapeutic effects compared to the DOX nanocrystals coated with the PEG-PCL. LNPs coated with CS and its derivatives exhibited significantly prolonged retention at various mucosal sites, thereby markedly improving the bioavailability of the loaded drugs.³⁴

The surface coating of NPs with CS mainly takes the following forms: (1) Layer-by-layer packaging of NPs by the positive and negative charge properties to minimize the adverse drug damage; (2) Formation of amide-bonded crosslinked CS shells by using its free radicals to encapsulate NPs. Zhang et al synthesized the NPs (TPP-PEG-ss-PLA) by grafting triphenylphosphine (TPP) onto poly (ethylene glycol) (PEG)-poly (D, L-propylene lactone) (PLA) copolymer.³¹ The surface of the NPs has a positive charge. The negative charge of CS is attracted to the positive charge of the NPs to form CS-coated NPs (CS/TPP-PEG-PLA@DOX). The final product is a multifunctional nanosystem with dual targeting of cell membranes and mitochondria, as well as dual responsiveness to pH and redox conditions. In vivo tests exhibited that this innovative therapeutic approach had considerable promise for the treatment of hepatocellular carcinoma. Abdelaziz et al prepared anionic LNPs by embedding positively charged pemetrexed-resveratrol-liquid crystalline NPs (PEM-RES-LCNP) into a negatively charged CS shell and then repeated with positively charged lactoferrin (LF). This layer-by-layer targeted modification prepares inhalable NPs that can significantly improve the therapeutic effects on lung cancer while minimizing damage to normal cells.³² Abd Elwakil et al employed negatively charged CS and positive LF to achieve layer-by-layer encapsulation of DOX and ellagic acid nanocrystals. The resulting NPs were coated for inhalation use in the treatment of lung cancer.¹¹⁵ Aly et al enclosed pterostilbene-loaded solid lipid nanoparticles (SLNs) with negatively charged CS and subsequently with positively charged LF. These dual-targeted NPs demonstrated remarkable antitumor efficacy in breast cancer models.¹¹⁶ Ren et al developed a pH- and glutathione-dual-responsive drug delivery system by using maleiminated polyethylene glycol and polylactide block copolymer as the core material. DOX was encapsulated within the nanoparticle, while thiocollagenase and maleimide were conjugated to the nanoparticle surface. To enhance stability and targeting, the NPs were further coated with CS as a protective layer. This design enabled the NPs to actively target CD44 receptors on cancer cells, resulting in enhanced anticancer efficacy in breast cancer-bearing mice.¹¹⁷

Luo et al used cationic liposomes consisting of soybean phosphatidylcholine, cholesterol and the positively charged lipid 1,2-dioleoyl-3-trimethylammonium propane to encapsulate the albumin-bound PTX complex (BSA-PTX). TPGS, a P-gp inhibitor, was then immobilized on its surface. Negatively charged CS was coated on its positively charged surface. The shell of CS can respond to the intra-tumor environment and accelerate the release of drugs for the effective treatment of drug-resistant breast cancer.¹¹⁸ Kim et al encapsulated cationic solid lipid NPs containing DTX with negatively charged glycoconjugate-CS conjugates. This orally administered drug demonstrated the capacity to maintain blood levels for 24 hours and exhibited potent anticancer efficacy, completely inhibiting tumor formation.¹¹⁹ Du et al used a method of physical encapsulation to improve the efficacy of NPs. The NPs were encapsulated by amide-bonded cross-linked CS shells (DOX@MOF-COD@CS). As the CS-encapsulated NPs reach the high-GSH intra-tumoral environment, the CS shell layer with disulfide bonds was disintegrated.¹²⁰ Furthermore, the nano-enzymes and natural enzymes initiated a cascade catalysis, which led to the conversion of cholesterol into hydroxyl radicals, providing a new idea for breast cancer cells to reverse drug resistance.¹²⁰ This approach diverges from charge-mediated encapsulation strategies, employing physical entrapment rather than electrostatic interactions for nanoparticle stabilization.

CS-Modified NPs

The presence of reactive groups of CS makes it highly suitable for the surface chemical modification of NPs. CS-modified and CS-coated NPs offer the primary goal of enhancing nanocarrier stability. However, their mechanisms of action exhibit distinct differences. CS-coated NPs achieve surface encapsulation through physical adsorption, whereas CS-modified NPs rely on covalent bond formation between reactive groups in CS molecules and functional groups on the NP surface. This covalent bonding strategy in CS-modified NPs circumvents desorption issues inherent to physical encapsulation, thereby conferring superior stability.¹²¹ Additionally, CS-modified NPs enable functional group integration, such as pH-responsive moieties for environment-sensitive drug release.⁷⁷ The covalent linkage ensures long-term stability in biological fluids, making CS-modified NPs particularly suitable for applications requiring prolonged circulation or site-specific drug delivery. Zhang et al prepared liposomal NPs chemically surfaced with CS from amphiphilic CS polymers for co-delivery of DOX and retinoic acid. The functionalized modification not only maintained the original drug loading capacity but also promoted the uptake of the particles by B16F10 and 4T1 cells, leading to the enhanced efficacy of the drug.¹²² Zu et al constructed the PLGA-based camptothecin (CPT)-loaded polymeric NPs with the surface modification by CS or carboxymethyl cellulose. The targeted CS-modified NPs with CPT encapsulation have demonstrated superior therapeutic outcomes compared to those with the surface of carboxymethyl cellulose.¹²³

CS binds to LNPs by chemical modification of their surfaces. Luo et al utilized the CS-modified dual drug-loading LNPs to deliver RA and DOX, intending to disrupt the Golgi apparatus and DNA to treat hepatocellular carcinoma. In vivo results demonstrated that DOX+RA-CSNs exhibited superior anti-cancer efficacy and effectively impeded tumor growth compared to LNPs devoid of CS modification (Figure 4).¹²⁴ Liu et al employed disulfide bonds to graft CS onto the surface of mesoporous silica NPs loaded with PTX and quercetin (QT). Surface modification of CS significantly improved the nanoparticle’s internalization kinetics. The residence time of the drug at the tumor site was prolonged, and tumor resistance was reversed.¹²⁵ Yu et al prepared photosensitizer indocyanine green (ICG)-loaded amorphous calcium-carbonate (ICG@) nanoparticle. Both ICG@ and DOX were encapsulated into PLGA-ss-CSA (PSC) nanoparticles. The resulting PSC/ICG@+DOX NPs exhibited pH- and reduction-responsive drug release, effective CD44 targeting and chemo-photothermal cancer therapy (Figure 5).⁷⁷

Figure 4 DOX+RA-CSNs target liver cancer cells via CD44-mediated endocytosis, then target Golgi apparatus via interaction with GalNAc-T. Reprinted from Carbohydrate Polymers, 249, Jingwen Luo, Tao Gong, Lixin Ma, Chondroitin-modified lipid nanoparticles target the Golgi to degrade extracellular matrix for liver cancer management, 116887, Copyright 2020, with permission from Elsevier.124 Abbreviations: DOCA, deoxycholic acid; i.v., intravenous injection; GalNAc-T, Golgi apparatus via interaction with N-acetylgalactosaminyltransferases.

Figure 5 PSC/ICG@+DOX exhibits pH and redox dual responses. Under laser irradiation, the synergistic treatment of chemotherapy and photothermal therapy has shown significant anti-cancer efficacy in 4T1-bearing mice. Reproduced with permission from Yu J, Wang L, Xie X, et al. Multifunctional nanoparticles codelivering doxorubicin and amorphous calcium carbonate preloaded with indocyanine green for enhanced chemo-photothermal cancer therapy. Int J Nanomed. 2023;18:323–337.77 Abbreviations: PSC, poly (lactic acid-hydroxyacetic acid copolymer)-ss-CSA; ICG, indocyanine green. Adapted from previous report (Reference 77).

Dendritic polymers are radially branched architectures and precisely controlled topological organization.^126,127 Due to their progressively controllable synthesis process, dendrimers combine the properties of both polymers and molecular chemistry. The inner cavity and peripheral functional groups of these polymers can be used to encapsulate bioactive molecules or chemically bond with bioactive molecules. The surface of dendrimer polymers could be modified with CS to target CD44 receptor. The potential of polyamidoamine (PAMAM) dendrimers for biomedical applications has been further enhanced by the modification with CS. Chen et al coupled CS with PAMAM via the Michael reaction to obtain the CS-PAMAM.¹²⁸ The polymeric nanoparticles were mixed with miR-34a, resulting in the formation of NPs containing miR-34a (CS-PAMAM/miR-34a). In vitro experiments indicated that the presence of CS as a targeting ligand further enhanced the transfection efficiency of miR-34a. CS-PAMAM/miR-34a demonstrated significant inhibition of lung adenocarcinoma growth in vivo and the ability to induce tumor cell apoptosis. Duan et al constructed the CS-PAMAM nanosystem for miR-34a delivery and used the human pancreatic cancer cell line MiaPaCa-2 as a model. Under the action of miR-34a, the NPs activated apoptosis and cell cycle arrest in pancreatic cancer cells, leading to significant suppression of cell proliferation and inhibition of cancer cell migration.¹²⁹

CS-Based Nanoplatform in Other Diseases Therapy

CS-based nanoplatforms play an important role in tumor therapy. Meanwhile, their applications have been extended to a variety of diseases such as ophthalmology, liver, and neurodegenerative diseases. In particular, CS exhibits significant anti-inflammatory activity, enhancing the bioavailability and targeting of nanoplatforms. This provides a highly effective strategy for the treatment of inflammation-related diseases.

Ophthalmic Diseases

Dry eye has a significant impact on the quality of life of patients, especially among an aging population.^130,131 CS with the targeting and adhesion properties may play a beneficial role in the treatment of dry eye. Zhu et al developed dexamethasone (DEX)-loaded CS-cysteine-functionalized cationic nanostructured lipid carriers (DEX-CS-Cys-cNLCs) through surface modification of cNLCs. The approach involved a coupling of CS and L-cysteine (CS-Cys) to create an ocular delivery system. The nanostructured carrier demonstrated stronger retention and duration of action. In addition, these NPs relieved dry eye symptoms, effectively repaired corneal damage and improved tear film stability.¹³² Tan et al reported the surface modification of DEX-loaded NLCs with (3-aminomethylphenyl)boronic acid-conjugated CS (APBA-CS). Compared with conventional ocular solutions, APBA has been shown to extend the retention time of the pharmaceutical agents within the cornea. APBA-CS exhibited strong mucoadhesive properties and therapeutic benefits for dry eye syndrome.¹³³ Abdullah et al found that CS-chitosan NPs facilitated the delivery of bromfenac sodium, leading to significantly high transcorneal permeation and corneal retention of bromfenac through the NPs. The NPs could be a potential vehicle for ocular drug delivery.¹³⁴ Corneal reinforcement is also of significance in the treatment of infectious corneal diseases, including conical corneas, corneal ulcers, and keratitis. Wang et al chemically modified CS with N-hydroxy succinimide (NHS) to obtain CS-NHS. The CS-NHS conjugate cross-linked with collagen and proteoglycans in the cornea, which could decrease the rate of dissolution and increase Young’s modulus, the diameter and the density of collagen fibers. Reduced expression of pro-inflammatory genes was also observed, while the cornea was strengthened. This method of corneal reinforcement is straightforward and efficacious.¹³⁵

Available commercial drugs for dry eye disease (DED) are predominantly focused on symptomatic treatment. CS-based nanoplatforms also follow this therapeutic principle. In the treatment of ophthalmic diseases, these nanoplatforms rely on enhanced permeability and mucosal adhesion for therapeutic purposes. This long-term action is particularly effective in relieving dry eye. Notably, CS-based nanocarriers could shift from symptom alleviation to targeting the underlying pathological mechanisms, thereby providing a novel therapeutic approach for DED.

Liver Diseases

Liver fibrosis is a critical stage in the progression of liver diseases towards cirrhosis, and existing pharmacotherapies have limited ability to halt or reverse this pathological progression.¹³⁶ CS-based NPs as an emerging therapeutic agent, have shown unique potential and advantages in reversing liver fibrosis. Zhang et al successfully prepared CS-modified lipid NPs by using phosphatidylcholine (PC), cholesterol, CS-PEG-DSPE, and PEG-DSPE. Subsequently, Vismodegib (VDG) was encapsulated into these NPs, resulting in formation of CS-NPs/VDG. It was found that CS-NP/VDG could effectively restore the pore structure of liver sinusoidal endothelial cells (LSECs) and inhibit the activation of hepatic stellate cells (HSCs). As previously described, CS was conjugated with 1-hexadecylamine (HDA) via an amide bond to yield the amphiphilic CS-HDA. The imatinib-encapsulated nanoparticles (IM-CS NPs) exhibited enhanced targeting efficiency toward activated HSCs and effectively suppressed HSC overactivation by modulating the PDGF and TGF-β signaling pathways.¹³⁷ Zhang et al reported that CS-modified, vismodegib-loaded nanoparticles (CS-NPs/VDG) effectively normalized the fenestrae phenotype of liver sinusoidal endothelial cells and restored HSCs to a quiescent state by inhibiting the Hedgehog signaling pathway.¹³⁸ Luo et al demonstrated that CS coated multilayered NPs encapsulating collagenase and silibinin (COL + SLB-MLPs) degraded the dense collagen stroma, while silibinin inhibited activated hepatic stellate cells. COL + SLB-MLPs were delivered to the cirrhotic liver, leading to the fact that silibinin and collagenase synergistically inhibited fibrosis in mice.¹³⁹ Cirrhosis represents a subsequent stage in the progression of liver fibrosis. Tan et al developed a novel modified nanoplatform (SRF-CS-PSA NPs) in which sorafenib (SRF) was loaded by palmitic acid-modified albumin (PSA) and further functionalized with CS. The resultant SRF-CS-PSA NPs exhibited dual targeting capabilities and inhibitory effects on HSCs and macrophages, which effectively reversed the process of cirrhosis.¹⁴⁰ Li et al constructed a multifunctional nanoparticle CREKA–CS–RA (CCR) based on CREKA (a specific ligand of fibronectin), CS (CD44 targeting ligand) and retinoic acid (RA, a Golgi apparatus-disturbing agent). Vismodegib-loaded CCR NPs disrupted the structure and function of Golgi apparatus, and inhibited the hedgehog signaling pathway, thus significantly suppressing hepatic stellate cells activation and extracellular matrix secretion.¹⁴¹

Neurodegenerative Diseases

Neurodegenerative diseases, particularly Alzheimer’s and Parkinson’s diseases, are becoming increasingly prevalent.^142,143 CS-based nanoplatforms showed great promise in the treatment of Alzheimer’s disease (AD). Tian et al developed a CS-modified MoS₂ nanoenzyme (CS@MoS₂) and evaluated its potential in anti-AD research. CS@MoS₂ demonstrated a substantial inhibitory effect on Aβ_1–40 aggregation and prevented toxic injury in SH-SY5Y cells, protecting cells from oxidative stress by modulating ROS and superoxide dismutase (SOD) activities. Furthermore, CS@MoS₂ facilitated a balanced intracellular Ca²⁺ level and down-regulated Tau phosphorylation via GSK-3β. In addition, CS@MoS₂ inhibited MAPK phosphorylation and the translocation of p-NF-κB (p65). These effects of CS@MoS₂ effectively improved learning, memory, and anxiety in D-gal/AlCl₃-induced AD mice.¹⁴⁴

Ji et al reported that CS nano-selenium CS@Se alleviated anxiety, enhanced learning and memory, reduced cellular edema and abscesses, protected mitochondria, and improved hippocampal neuronal synaptic structure in AD mice. In addition, CS@Se increased SOD, glutathione peroxidase (GSH-Px), Na⁺/K⁺-ATPase and choline acetyltransferase levels, and decreased malondialdehyde and acetylcholinesterase levels. CS@Se regulated GSK-3β expression, attenuated Tau protein hyperphosphorylation, activated extracellular signal-regulated kinase 1/2, and p38 mitogen-activated protein kinase signaling pathways, inhibited nuclear transcription factor kappa B (NF-κB) nuclear translocation, and regulated pro-inflammatory cytokine expression. These effects delayed the development of AD and enhanced cognitive performance in mice.¹⁴⁵ Gao et al ascertained that CS@Se effectively inhibited the aggregation of β-amyloid (Aβ), reduced damage to the cytoskeleton, attenuated oxidative stress and the hyperphosphorylation of Tau protein.¹⁴⁶ Hence, CS@Se had the potential as a potential multifunctional drug for the treatment of AD. Feng et al constructed a transmembrane peptide-CS‑gold nanoparticle (TAT-CS@Au) nanoparticle, which exhibited favorable cellular uptake and transport ability, and effectively inhibited Aβ_1–40 accumulation and reduced apoptosis, thereby alleviating oxidative stress and cholinergic damage by regulating the levels of ROS, malondialdehyde, GSH-Px and acetylcholine. Furthermore, TAT-CS@Au nanoparticle could inhibit Tau phosphorylation, NF-κB nuclear translocation, and the production of inflammatory factors, thus providing a novel and promising approach to anti-AD therapy.¹⁴⁷

The treatment of AD poses significant challenges. Previous therapeutic interventions have predominantly concentrated on alleviating symptoms. Specifically, CS-based nanoplatforms focused on the underlying mechanisms that facilitate disease progression, which could lead to a potential treatment for AD.

Inflammation

CS possesses inherent anti-inflammatory properties. However, its therapeutic efficacy via oral administration has been limited due to poor bioavailability. To overcome this challenge, researchers developed a CS-based nanoscale delivery system. This platform enabled the controlled release of anti-inflammatory agents while simultaneously generating bioactive CS fragments from the nanocarrier itself. This dual-action mechanism synergistically enhanced the anti-inflammatory effect by combining pharmacological intervention with the intrinsic therapeutic activity of the carrier material. In recent years, CS-based nanoplatforms have demonstrated significant potential in the treatment of inflammatory diseases, such as ulcerative colitis (UC), rheumatoid arthritis, osteoarthritis, and periodontitis.^148–151

As previously described, rosmarinic acid-CSA nanoconjugate was synthesized. The drug-conjugated nanoassemblies significantly attenuated colonic inflammation compared to free rosmarinic acid in dextran sulfate sodium-induced acute colitis mouse model.⁴⁸ Deng et al developed licofelone-loaded NPs (LCF-CSBN) composed of CS and bilirubin. These NPs effectively alleviated joint inflammation, oxidative stress and cartilage degeneration in osteoarthritis model rats.¹⁵² As previously studied, intra-articular nanohybrids were developed for the co-delivery of CS, glucosamine sulfate and gold, aiming to achieve synergistic anti-inflammatory and cartilage regenerative effects.¹⁵³ Dubashynskaya et al used CS and diethylaminoethyl chitosan (DeaeCS) to prepare dexamethasone phosphate (DexP)-loaded NPs (Dexp-CHS-DeaeCS-Zn). The study found that Zn²⁺-containing NPs exhibited relatively small dimensions. This phenomenon resulted in the sustained release of DexP from the NPs. The combination of the NPs’ mucosal adhesion and prolonged drug release contributed to a favorable anti-inflammatory effect. The alteration of the ratio of anionic and cationic polymers, with consideration for the charged nature of the bound NPs, offers a novel approach to the regulation of drug release.¹⁴⁸

Cesar et al prepared CS-5-ASA by coupling mesalazine (5-ASA) and CS. The CS-5-ASA was selected for the intestinal environment and acted as an adhesive in the colon. This finding suggested that the nanoparticle could be used as an alternative therapy for UC.¹⁵⁴ Egg white-derived peptides (EWDP) and hydrophobic quercetin were encapsulated into oral colon-targeting NPs by using Zein/CS templates. EWDP co-assembled with the actively targeting CS polymers, promoting enhanced colon-specific accumulation of the NPs. This targeted delivery significantly repaired the intestinal barrier and restored gut microbiota balance.¹⁵⁵ Wang et al investigated the potential of CS-Zein NPs in the delivery of magnolol to enhance the anti-inflammatory effects of colon inflammation. The findings revealed that the help of NPs resulted in enhanced Mag accumulation in the inflamed colon and improved cellular uptake. Further, in vivo studies demonstrated that the use of this nanoparticle in conjunction with a hydrogel modulated cytokine expression levels, leading to the treatment of colitis and the restoration of the mucosal barrier in mice.¹⁵⁶ Chen et al reported the synthesis of EGCG-PVP-CS (EPC) by conjugating epigallocatechin gallate (EGCG) with poly(N-vinylpyrrolidone) (PVP) and the polysaccharide CS. This formulation enhanced the antioxidant capacity of the natural polyphenol EGCG. Both in vivo and in vitro experiments demonstrated that EPC exhibited strong reactive oxygen species (ROS) scavenging activity and effectively inhibited colitis in a mouse model of UC. These findings provide valuable data supporting the potential clinical application of polyphenols in the treatment of inflammatory diseases.¹⁵⁷ Gou et al demonstrated that surface modification of curcumin-loaded NPs with CS enabled targeted delivery of curcumin to macrophages, resulting in enhanced anti-inflammatory effects. Animal studies further confirmed that this CS-modified nanocarrier exerted a therapeutic effect in alleviating symptoms of UC.¹⁵⁸ Jiang et al highlighted the importance of CS-based targeting strategies for the treatment of colitis. Upon surface modification with CS, tetrasulfide-containing organosilica NPs (DSMSNs) not only improved the solubility of resveratrol (Res) and enhanced its cellular uptake but also facilitated its release in the intracellular environment. The observed alleviation of colitis symptoms in a disease model supported this approach as a novel concept for the oral treatment of UC.¹⁵⁹

Matos Oliveira et al immobilized TNF-α antibodies onto CS/PAMAM dendrimer NPs. The combined anti-TNF-α activity of the CS and antibodies, demonstrated in inflammatory models, offers a promising therapeutic strategy for various inflammatory conditions, including rheumatoid arthritis.¹⁴⁹ Zewail et al encapsulated leflunomide nanocapsules (NCAPs) with CS, resulting in a higher maximum concentration (Cmax), greater area under the curve (AUC), and lower TNF-α levels compared to the formulations encapsulated with chitosan. The dual advantages of CS-inherent anti-inflammatory properties and active targeting capability enabled CS-coated NLCs to exhibit promising anti-inflammatory potential in a rat model of rheumatoid arthritis.¹⁶⁰ Sun et al reported that grafting CS onto the surface of curcumin-tragacanth gum-gelatin composite nanocapsules (TGNCs) enabled targeted delivery to macrophages, leading to enhanced cellular uptake. This modification resulted in superior accumulation at joint sites compared to the NPs without CS. In the treatment of rheumatoid arthritis, CS-Cur-TGNCs promoted the polarization of macrophages from M2 phenotype to M1 phenotype, while simultaneously reducing the expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6. Moreover, this strategy significantly alleviated joint swelling in a gouty arthritis (GA) rat model.³⁰

Bishnoi et al conjugated CS to a non-targeted nanovesicle formulation (MB-NV) to develop a sublingual formulation, C-MB-NV, with targeted delivery.¹⁵⁰ This formulation enabled the sublingual administration of tapentadol HCl, effectively bypassing first-pass effects. It demonstrated improved pharmacokinetic parameters compared to the non-targeted formulation, reducing the risk of addiction and providing sustained analgesic effects. This study offers preclinical data supporting the use of this approach in the treatment of osteoarthritis. Yin et al reported that the addition of CS to the surface of platinum NPs (ptNPs) enhanced their biocompatibility with osteoarthritic chondrocytes. This environmentally friendly nanoparticle preparation method, which avoids the use of harmful chemicals, shows significant potential for the treatment of osteoarthritis.¹⁶¹ Qu et al synthesized polyethyleneimine (PEI)-modified CS derivatives (PEI-CS) for the targeted delivery of oligodeoxyribonucleotide (ODN) YW002. This nanoparticle effectively protected ODN YW002 from premature inactivation, reduced the expression of pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α in RAW246.7 cells, and demonstrated the ability to inhibit periodontitis in mice. These findings suggested that PEI-CS NPs had significant potential as a therapeutic approach for the treatment of periodontitis.¹⁵¹ Notably, CS-based nanoplatforms have shown broad potential in anti-inflammatory therapies, an area that has become a prominent focus of research. However, to maximize their therapeutic effectiveness, strategies are needed to overcome the limitations of single therapeutic modalities. Emerging research trends indicate that integrating synergistic approaches could enhance anti-inflammatory efficacy. For instance, He et al reported that methacrylated gelatin-magnetic nanocomposites, when combined with laser irradiation, significantly reduced levels of key pro-inflammatory factors such as TNF-α and IL-1β. This finding may offer valuable insights for advancing anti-inflammatory applications.¹⁶²

CS-Based Nanoplatform in Tissue Engineering

The ECM consists of a complex network of proteins, proteoglycans, and other biomolecules.¹⁶³ The combination of NPs with ECM-based materials can more effectively facilitate drug targeting and promote tissue-specific cell differentiation, offering significant benefits for tissue engineering development.¹⁶³ Polymer-based scaffolds have been utilized to enhance tissue regeneration by mimicking the physical properties of native tissues.¹⁶⁴ The intrinsic biochemical cues of ECM-derived materials can enhance nanoparticle-targeted drug delivery and provide additional bioactivity for wound healing and regenerative medicine.¹⁶³ CS, as a component of the ECM, plays a crucial and dynamic structural role within the matrix.¹⁶⁵ CS can be integrated with nanofiber scaffolds to simulate the ECM environment of cartilage, thereby maintaining the chondrocyte phenotype while promoting cell adhesion, proliferation, and ECM secretion. For instance, a nanofiber scaffold composed of poly(vinyl alcohol) and bio-inspired CS, with fibers at the nanoscale, has been applied for articular cartilage repair.¹⁶⁶ Compared to traditional particle culture, this nanofiber scaffold not only enhanced the chondrogenic differentiation of mesenchymal stem cells but also increased ECM production and the expression of cartilage-specific genes, while supporting cell proliferation. The improved formation of cartilage tissue observed with this scaffold underscores its potential in articular cartilage repair.¹⁶⁶ Furthermore, 3D electrospun nanofiber scaffolds have been developed for cartilage regeneration. Chen et al advanced this approach by crosslinking CS onto the 3D scaffold. This functionalization leverages CS’s excellent properties in promoting cartilage regeneration and its potential in immune regulation.¹⁶⁷

CS-based nanofiber scaffolds have promising applications in wound healing. Researchers have prepared a polyelectrolyte complex using chitosan and CS, which formed an in-situ scaffold via spontaneous mixing. This scaffold demonstrates excellent blood compatibility and potent antibacterial activity, while simultaneously stimulating fibroblast proliferation to facilitate wound healing, positioning it as an ideal candidate for wound dressings.¹⁶⁸ Place et al reported that polyelectrolyte composite nanoparticles (PCNs) formed by the complexation of anionic and cationic polysaccharides could effectively simulate the function of aggrecan.¹⁶⁹ The cationic polysaccharides chitosan and N, N, N-trimethyl chitosan (TMC) are complexed with the anionic GAGs heparin (Hep) and CS in solution with the polyanion in excess. The resulting PCNs have a colloidally stable, negatively charged structure that closely mimics the size and chemical characteristics of aggrecan. CS-based aggrecan mimetics are as effective as aggrecan, and these PCNs can be applied either in soluble form or bound to surfaces for targeted growth factor delivery. This strategy holds significant promise for enhancing the therapeutic delivery of Hep-binding growth factors and cytokines in tissue engineering and wound healing applications.

Due to its inherently low mechanical strength and limited load-bearing capacity, CS is often combined with other materials, thereby broadening its range of applications. However, the synthesis of CS-based NPs typically involves complex chemical modifications and processing steps, which raise production costs and present technical challenges. Future research should focus on developing more efficient preparation methods to enhance the applicability of CS-based nanoplatforms in bone repair and wound healing.

CS-Based Nanoplatform in Biological Sensing

CS can participate in the construction of biosensors based on a series of nanomaterials, such as gold NPs (AuNPs) and quantum dots. It can be used as a recognition element or stabilizer for the detection of biomolecules, especially some tumor markers. For example, CS can be modified on the surface of AuNPs. AuNPs have excellent performance, high sensitivity, simplicity, and low cost in colorimetric detection, and can be used as colorimetric probes for detecting chemicals, ions and biomolecules. Noh et al demonstrated that CS-reduced AuNPs (CS-AuNPs) could be effectively used for melamine detection in infant formula, offering rapid and reliable sensing capabilities.¹⁷⁰ CS has negatively charged groups that interact with cations, especially metal cations. Therefore, it could be an asset in the development of new materials for the detection, extraction, or separation of heavy metals. For example, Santos et al reported that metal cation optosensing membranes were improved through the incorporation of sulfated polysaccharides. It has a stronger interaction with metal cations and can form more chromophore complexes, ultimately leading to an increase in the intensity signal given by the complex formation.¹⁷¹ The photosensitive film with CS added exhibited a low detection limit and excellent selectivity for detecting heavy metals. Xu et al developed an antifouling electrochemical biosensor based on CS-functionalized polyaniline (CS/PANI) and DNA-peptide conjugates, capable of directly detecting cortisol in bodily fluids such as sweat, saliva and tears.¹⁷² The antifouling properties of CS, combined with its interaction capabilities, improved the biosensor’s sensitivity and performance in biological environments. Additionally, Zhao et al developed of a novel electrochemical biosensor based on Fe₃O₄@Au@polyethylene glycol (PEG)@CS NPs.¹⁷³ This biosensor demonstrated ultra-low pollution characteristics in complex biological systems, along with high selectivity, reproducibility and storage stability. Notably, it was successfully used to detect Mycoplasma pneumoniae in whole serum, showcasing its clinical diagnostic potential.

Dysregulation of glycosaminoglycan (GAG)-cleaving enzymes in vivo is associated with numerous human diseases, including cancer, diabetes, atherosclerosis, arthritis, inflammation, and cardiovascular disorders.¹⁷⁴ CS can be covalently conjugated to fluorescent dyes and subsequently immobilized onto AuNPs to construct nanosensors that serve as excellent substrates for GAG lyase.¹⁷⁴ Upon treatment with GAG lyase, these nanosensors release dye-labeled oligosaccharides or disaccharides from the AuNPs, thereby enhancing fluorescence recovery. These nanosensors can serve as diagnostic tools for detecting dysregulation of GAG cleavage enzyme expression. Furthermore, CS-based biosensors have scientific significance and applications in seawater aquaculture and the prevention of foodborne diseases. The amino groups in CS exhibit strong proton-accepting capabilities, enhancing hydration upon protonation and forming a dense hydration layer that improves the material’s antifouling performance. For instance, an antifouling electrochemical biosensor was developed by using CS-functionalized polyaniline (CS/PANI) combined with DNA-peptide conjugates, enabling the direct assay of cortisol in human fluids.¹⁷² The inherent antifouling properties of both CS and the DNA-peptide conjugates contribute to the biosensor’s exceptional detection sensitivity.

CS-based NPs are well-suited for the real-time monitoring of biomarkers such as glucose, proteins and nucleic acids, and are widely employed in disease diagnosis and health data monitoring. However, in complex biological samples, interfering components can compromise the detection signal. Therefore, enhancing the selectivity of CS-based NPs remains a critical issue in biosensing applications for further improvement.

Conclusions

Overall, significant progress has been made in disease therapy, tissue repair and biosensing through the use of CS-based nanoplatforms. These platforms not only complement the shortcomings of chemotherapy but also help reduce tumor cell drug resistance. Their unique physicochemical properties, including targeted delivery, redox and pH responsiveness, and sensitivity to enzymes and other environmental factors, have enabled them to exhibit superior anti-tumor potency in specific therapies. Moreover, the integration of emerging strategies has considerably expanded the potential of these nanoplatforms in synergistic treatment approaches.

In addition to their applications in anti-tumor therapy, CS-based nanoplatforms showed promising prospects for treating ophthalmic diseases, liver diseases, neurodegenerative disorders and various inflammatory conditions. These studies suggested that CS nanoplatforms not only served as effective drug carriers that enhanced therapeutic efficacy but also exerted synergistic effects through their inherent anti-inflammatory properties. Furthermore, integrating CS with nanofibrous scaffolds offered innovative solutions for cartilage repair and wound healing. Interestingly, the incorporation of CS into biosensors enabled the accurate monitoring of trace substances and their expression, highlighting its significant potential for practical applications.

Despite the promising results observed in experimental studies, extensive clinical trials are necessary to validate the transition of CS-based nanoplatforms from the laboratory to clinical applications. The unique properties of CS extend beyond cancer treatment, warranting exploration of its potential in other medical fields. Future research should focus on designing comprehensive clinical trials to thoroughly assess the safety, efficacy, and feasibility of these nanoplatforms, thereby providing robust data to support the development of anticancer therapies and treatments for other diseases.

Acknowledgments

This work was sponsored by the Science and Technology Plan Project of Huzhou City (No. 2022GZ44).

Disclosure

The authors report no conflicts of interest in this work.

References

1. Tordi P, Ridi F, Samori P, et al. Cation-alginate complexes and their hydrogels: a powerful toolkit for the development of next-generation sustainable functional materials. Adv Funct Mater. 2025;35(9):2416390. doi:10.1002/adfm.202416390

2. Tu LX, Xing BH, Ma SF, et al. A review on polysaccharide-based tumor targeted drug nanodelivery systems. Int J Biol Macromol. 2025;304:140820. doi:10.1016/j.ijbiomac.2025.140820

3. Hu XT, Xie DP, Li YW, et al. A dual-modified glucomannan polysaccharide selectively sequesters growth factors for skin tissue repair. J Control Release. 2025;380:185–198. doi:10.1016/j.jconrel.2025.01.093

4. Azimijou N, Karimi-Soflou R, Karkhaneh A. CD44 targeted-chondroitin sulfate nanoparticles: fine-tuning hydrophobic groups to enhance in vitro pH-responsiveness and in vivo efficacy for advanced breast cancer treatment. Biomater Adv. 2024;158:213776. doi:10.1016/j.bioadv.2024.213776

5. Volpi N. Chondroitin sulfate safety and quality. Molecules. 2019;24:1447. doi:10.3390/molecules24081447

6. Fajardo AR, Guerry A, Britta EA, et al. Sulfated glycosaminoglycan-based block copolymer: preparation of biocompatible chondroitin sulfate-b-poly(lactic acid) micelles. Biomacromolecules. 2014;15:2691–2700. doi:10.1021/bm5005355

7. Liu H, Wu S, Yu J, et al. Reduction-sensitive micelles self-assembled from amphiphilic chondroitin sulfate A-deoxycholic acid conjugate for triggered release of doxorubicin. Mat Sci Eng C. 2017;75:55–63. doi:10.1016/j.msec.2017.02.030

8. Rajesh A, Sajeev D, Kumaar RN, et al. Chondroitin sulfate: from bioactive molecule to versatile drug delivery system for advancing regenerative medicine. Int J Biol Macromol. 2025;311:143746. doi:10.1016/j.ijbiomac.2025.143746

9. du Souich P, Garcia AG, Verges J, et al. Immunomodulatory and anti-inflammatory effects of chondroitin sulphate. J Cell Mol Med. 2009;13:1451–1463. doi:10.1111/j.1582-4934.2009.00826.x

10. Sugiura N, Shioiri T, Chiba M, et al. Construction of a chondroitin sulfate library with defined structures and analysis of molecular interactions. J Biol Chem. 2012;287:43390–43400. doi:10.1074/jbc.M112.412676

11. Lee CT, Huang CP, Lee YD. Synthesis and characterizations of amphiphilic poly(L-lactide)-grafted chondroitin sulfate copolymer and its application as drug carrier. Biomol Eng. 2007;24:131–139. doi:10.1016/j.bioeng.2006.05.010

12. Wang X, Huang YX, Yang YL, et al. Polysaccharide-based biomaterials for regenerative therapy in intervertebral disc degeneration. Mater Today Bio. 2025;30:101395. doi:10.1016/j.mtbio.2024.101395

13. Shen QS, Guo YJ, Wang KY, et al. A review of chondroitin sulfate’s preparation, properties, functions, and applications. Molecules. 2023;28:7093. doi:10.3390/molecules28207093

14. Sharma R, Kuche K, Thakor P, et al. Chondroitin sulfate: emerging biomaterial for biopharmaceutical purpose and tissue engineering. Carbohydr Polym. 2022;286:119305. doi:10.1016/j.carbpol.2022.119305

15. Wu JL, Li YY, Sun SJ, et al. The pH-sensitive chondroitin sulphate-based nanoparticles for co-delivery of doxorubicin and berberine enhance the treatment of breast cancer. Int J Biol Macromol. 2024;281:136484. doi:10.1016/j.ijbiomac.2024.136484

16. Beach MA, Nayanathara U, Gao YT, et al. Polymeric nanoparticles for drug delivery. Chem Rev. 2024;124:5505–5616. doi:10.1021/acs.chemrev.3c00705

17. Peng XQ, Fang JJ, Lou CY, et al. Engineered nanoparticles for precise targeted drug delivery and enhanced therapeutic efficacy in cancer immunotherapy. Acta Pharm Sin B. 2024;14:3432–3456. doi:10.1016/j.apsb.2024.05.010

18. Ren J, Liang L, Yang YQ, et al. Assembling drug-loaded-layered double hydroxide nanohybrids with poloxamer 188 for improved cellular uptake and in vitro efficacy. J Mater Res. 2023;38:337–349. doi:10.1557/s43578-022-00813-w

19. Chaurasia M, Pawar VK, Jaiswal AK, et al. Chondroitin nanocapsules enhanced doxorubicin induced apoptosis against leishmaniasis via Th1 immune response. Int J Biol Macromol. 2015;79:27–36. doi:10.1016/j.ijbiomac.2015.04.043

20. Egwu CO, Aloke C, Onwe KT, et al. Nanomaterials in drug delivery: strengths and opportunities in medicine. Molecules. 2024;29:2584. doi:10.3390/molecules29112584

21. Xie W, Wang H, Xu H, et al. Sterically chained amino acid-rich water-soluble carbon quantum dots as a robust tumor-targeted drug delivery platform. Nat Commun. 2025;16:2716. doi:10.1038/s41467-025-57531-0

22. Liu L, Tu B, Sun Y, et al. Nanobody-based drug delivery systems for cancer therapy. J Control Release. 2025;381:113562. doi:10.1016/j.jconrel.2025.02.058

23. Lee JH, Yang SB, Park SJ, et al. Cell-penetrating peptide like anti-programmed cell death-ligand 1 peptide conjugate-based self-assembled nanoparticles for immunogenic photodynamic therapy. ACS Nano. 2025;19:2870–2889. doi:10.1021/acsnano.4c16128

24. Ooki T, Hatakeyama M. Hyaluronan degradation promotes cancer via Hippo-YAP signaling: an intervention point for cancer therapy. Bioessays. 2020;42:2000005. doi:10.1002/bies.202000005

25. Khan I, Saeed K, Khan I. Nanoparticles: properties, applications and toxicities. Arab J Chem. 2019;12:908–931. doi:10.1016/j.arabjc.2017.05.011

26. Li Y, Hou H, Liu Z, et al. CD44 targeting nanodrug based on chondroitin sulfate for melanoma therapy by inducing mitochondrial apoptosis pathways. Carbohyd Polym. 2023;320:121255. doi:10.1016/j.carbpol.2023.121255

27. Li K, Xu K, Liu SP, et al. All-in-one engineering multifunctional nanoplatforms for sensitizing tumor low-temperature photothermal therapy in vivo. ACS Nano. 2023;17:20218–20236. doi:10.1021/acsnano.3c05991

28. Ai Y, Tian Y, Qiao J, et al. “Yin-Yang philosophy” for the design of anticancer drug delivery nanoparticles. Biomater Transl. 2024;5:144–156. doi:10.12336/biomatertransl.2024.02.005

29. Xie X, Yuan Z, Yuan Q, et al. Preparation and characterization of amphiphilic nanoparticles based on chondroitin sulfate A conjugated with hydrophobic drug for enhanced doxorubicin delivery. Colloid Polym Sci. 2021;299:129–136. doi:10.1007/s00396-020-04778-2

30. Sun J, Du J, Liu X, et al. Chondroitin sulfate-modified tragacanth gum-gelatin composite nanocapsules loaded with curcumin nanocrystals for the treatment of arthritis. J Nanobiotechnol. 2024;22:270. doi:10.1186/s12951-024-02540-2

31. Zhang X, Wang Y, Wei G, et al. Stepwise dual targeting and dual responsive polymer micelles for mitochondrion therapy. J Control Release. 2020;322:157–169. doi:10.1016/j.jconrel.2020.03.011

32. Abdelaziz HM, Elzoghby AO, Helmy MW, et al. Inhalable lactoferrin/chondroitin-functionalized monoolein nanocomposites for localized lung cancer targeting. ACS Biomater Sci Eng. 2020;6:1030–1042. doi:10.1021/acsbiomaterials.9b01639

33. Abourehab MAS, Baisakhiya S, Aggarwal A, et al. Chondroitin sulfate-based composites: a tour d’horizon of their biomedical applications. J Mater Chem B. 2022;10:9125–9178. doi:10.1039/d2tb01514e

34. Vijayakumar S, González-Sánchez ZI, Divya M, et al. Efficacy of chondroitin sulfate as an emerging biomaterial for cancer-targeted drug delivery: a short review. Int J Biol Macromol. 2024;283:137704. doi:10.1016/j.ijbiomac.2024.137704

35. Liu B, Zhou H, Tan L, et al. Exploring treatment options in cancer: tumor treatment strategies. Signal Transduct Target. 2024;9:175. doi:10.1038/s41392-024-01856-7

36. Khan AR, Yang X, Du X, et al. Chondroitin sulfate derived theranostic and therapeutic nanocarriers for tumor-targeted drug delivery. Carbohydr Polym. 2020;233:115837. doi:10.1016/j.carbpol.2020.115837

37. Shi Y, van der Meel R, Chen X, et al. The EPR effect and beyond: strategies to improve tumor targeting and cancer nanomedicine treatment efficacy. Theranostics. 2020;10:7921–7924. doi:10.7150/thno.49577

38. Chen G, Deng SH, Liu SB, et al. pH and ROS dual-sensitive nanocarriers for the targeted co-delivery and on-demand sequential release of tofacitinib and glucosamine for synergistic rheumatoid arthritis treatment. Small. 2024;20:2308520. doi:10.1002/smll.202308520

39. Jiang RL, Liu HN, Yang YF, et al. Zwitterionic hyaluronic acid derivatives for co-delivery of both chemotherapeutic and nucleic acid drugs in breast cancer treatment. Nano Res. 2025;18:94907076. doi:10.26599/nr.2025.94907076

40. Chen G, Deng S, Liu S, et al. pH and ROS dual-sensitive nanocarriers for the targeted co-delivery and on-demand sequential release of Tofacitinib and Glucosamine for synergistic rheumatoid arthritis treatment. Small. 2024;20:e2308520. doi:10.1002/smll.202308520

41. Yaghobi Z, Movassaghpour A, Talebi M, et al. The role of CD44 in cancer chemoresistance: a concise review. Eur J Pharmacol. 2021;903:174147. doi:10.1016/j.ejphar.2021.174147

42. Li M, Sun J, Zhang W, et al. Drug delivery systems based on CD44-targeted glycosaminoglycans for cancer therapy. Carbohydr Polym. 2021;251:117103. doi:10.1016/j.carbpol.2020.117103

43. Onishi H, Fukasawa A, Miatmoko A, et al. Preparation of chondroitin sulfate-adipic acid dihydrazide-doxorubicin conjugate and its antitumour characteristics against LLC cells. J Drug Target. 2017;25:747–753. doi:10.1080/1061186x.2017.1327593

44. Liang Y, Fu X, Du C, et al. Enzyme/pH-triggered anticancer drug delivery of chondroitin sulfate modified doxorubicin nanocrystal. Artif Cells Nanomed Biotechnol. 2020;48:1114–1124. doi:10.1080/21691401.2020.1813741

45. Amhare AF, Lei J, Deng H, et al. Biomedical application of chondroitin sulfate with nanoparticles in drug delivery systems: systematic review. J Drug Target. 2021;29:259–268. doi:10.1080/1061186x.2020.1833018

46. Pandey G, Mittapelly N, Banala VT, et al. Multifunctional glycoconjugate assisted nanocrystalline drug delivery for tumor targeting and permeabilization of lysosomal-mitochondrial membrane. ACS Appl Mater Interfaces. 2018;10:16964–16976. doi:10.1021/acsami.7b18699

47. Mohtashamian S, Boddohi S, Hosseinkhani S. Preparation and optimization of self-assembled chondroitin sulfate-nisin nanogel based on quality by design concept. Int J Biol Macromol. 2018;107:2730–2739. doi:10.1016/j.ijbiomac.2017.10.156

48. Long MM, Li J, Yang MY, et al. Rosmarinic acid-chondroitin sulfate nanoconjugate for targeted treatment of ulcerative colitis. Int J Biol Macromol. 2025;306:141008. doi:10.1016/j.ijbiomac.2025.141008

49. Imamura M, Kodama Y, Higuchi N, et al. Ternary complex of plasmid DNA electrostatically assembled with polyamidoamine dendrimer and chondroitin sulfate for effective and secure gene delivery. Biol Pharm Bull. 2014;37:552–559. doi:10.1248/bpb.b13-00768

50. Fernandez-Piñeiro I, Pensado A, Badiola I, et al. Development and characterisation of chondroitin sulfate- and hyaluronic acid-incorporated sorbitan ester nanoparticles as gene delivery systems. Eur J Pharm Biopharm. 2018;125:85–94. doi:10.1016/j.ejpb.2018.01.009

51. Rasoulianboroujeni M, Kang RH, Klukas M, et al. Crystallization of supersaturated PEG-b-PLA for the production of drug-loaded polymeric micelles. J Control Release. 2025;380:457–468. doi:10.1016/j.jconrel.2025.02.009

52. Ghosh B, Biswas S. Polymeric micelles in cancer therapy: state of the art. J Control Release. 2021;332:127–147. doi:10.1016/j.jconrel.2021.02.016

53. Ao H, Fu Y, Wang X. A comparative study of PEO-PBO content on the targeting and anti-glioma activity of annonaceous acetogenins-loaded nanomicelles. Colloid Surf B. 2024;244:114176. doi:10.1016/j.colsurfb.2024.114176

54. Liu M, Du H, Zhai G. Self-assembled nanoparticles based on chondroitin sulfate-deoxycholic acid conjugates for docetaxel delivery: effect of degree of substitution of deoxycholic acid. Colloid Surf B. 2016;146:235–244. doi:10.1016/j.colsurfb.2016.06.019

55. Gaber M, Elhasany KA, Sabra S, et al. Co-administration of tretinoin enhances the anti-cancer efficacy of etoposide via tumor-targeted green nano-micelles. Colloid Surf B. 2020;192:110997. doi:10.1016/j.colsurfb.2020.110997

56. Yu C, Gao C, Lu S, et al. Facile preparation of pH-sensitive micelles self-assembled from amphiphilic chondroitin sulfate-histamine conjugate for triggered intracellular drug release. Colloid Surf B. 2014;115:331–339. doi:10.1016/j.colsurfb.2013.12.023

57. Luo J, Zhang P, Zhao T, et al. Golgi apparatus-targeted chondroitin-modified nanomicelles suppress hepatic stellate cell activation for the management of liver fibrosis. ACS Nano. 2019;13:3910–3923. doi:10.1021/acsnano.8b06924

58. Elhasany KA, Khattab SN, Bekhit AA, et al. Combination of magnetic targeting with synergistic inhibition of NF-κB and glutathione via micellar drug nanomedicine enhances its anti-tumor efficacy. Eur J Pharm Biopharm. 2020;155:162–176. doi:10.1016/j.ejpb.2020.08.004

59. Yu J, Yuan Q, Li C, et al. Reactive oxygen species-sensitive chondroitin sulfate A-cholesteryl hemisuccinate micelles for targeted doxorubicin delivery in tumor therapy. J Drug Deliv Sci Tec. 2024;96:105690. doi:10.1016/j.jddst.2024.105690

60. Jeong D, Bae BC, Park SJ, et al. Reactive oxygen species responsive drug releasing nanoparticle based on chondroitin sulfate-anthocyanin nanocomplex for efficient tumor therapy. J Control Release. 2016;222:78–85. doi:10.1016/j.jconrel.2015.12.009

61. Zhang Y, Zhou J, Chen X, et al. Modulating tumor-stromal crosstalk via a redox-responsive nanomedicine for combination tumor therapy. J Control Release. 2023;356:525–541. doi:10.1016/j.jconrel.2023.03.015

62. Wang X-F, Ren J, He H-Q, et al. Self-assembled nanoparticles of reduction-sensitive poly (lactic-co-glycolic acid)-conjugated chondroitin sulfate A for doxorubicin delivery: preparation, characterization and evaluation. Pharm Dev Technol. 2019;24:794–802. doi:10.1080/10837450.2019.1599914

63. Cai S, Xie X, Yuan Q, et al. Preparation and evaluation of reduction-responsive micelles based on disulfide-linked chondroitin sulfate A-tocopherol succinate for controlled antitumour drug release. J Pharm Pharmacol. 2021;73:1405–1417. doi:10.1093/jpp/rgab096

64. Liu M, Du H, Khan AR, et al. Redox/enzyme sensitive chondroitin sulfate-based self-assembled nanoparticles loading docetaxel for the inhibition of metastasis and growth of melanoma. Carbohydr Polym. 2018;184:82–93. doi:10.1016/j.carbpol.2017.12.047

65. Yu J, Xie X, Wang L, et al. Smart chondroitin sulfate micelles for effective targeted delivery of doxorubicin against breast cancer metastasis. Int J Nanomed. 2023;18:663–677. doi:10.2147/IJN.S398802

66. Yu J, Wang L, Ling Y, et al. Peptide-modified bioresponsive chondroitin sulfate micelles for targeted doxorubicin delivery in triple-negative breast cancer. Colloid Surf B. 2023;227:113381. doi:10.1016/j.colsurfb.2023.113381

67. Zhang H, Xu J, Xing L, et al. Self-assembled micelles based on chondroitin sulfate/poly (D,L-lactideco-glycolide) block copolymers for doxorubicin delivery. J Colloid Interf Sci. 2017;492:101–111. doi:10.1016/j.jcis.2016.12.046

68. Luo Y, Yan P, Li X, et al. pH-sensitive polymeric vesicles for GOx/BSO delivery and synergetic starvation-ferroptosis therapy of tumor. Biomacromolecules. 2021;22:4383–4394. doi:10.1021/acs.biomac.1c00960

69. Du N, Song LP, Li XS, et al. Novel pH-sensitive nanoformulated docetaxel as a potential therapeutic strategy for the treatment of cholangiocarcinoma. J Nanobiotechnol. 2015;13:17. doi:10.1186/s12951-015-0066-8

70. Yu J, Xu J, Jiang R, et al. Versatile chondroitin sulfate-based nanoplatform for chemo-photodynamic therapy against triple-negative breast cancer. Int J Biol Macromol. 2024;265:130709. doi:10.1016/j.ijbiomac.2024.130709

71. Zhang Y, Khan AR, Yang X, et al. A sonosensitiser-based polymeric nanoplatform for chemo-sonodynamic combination therapy of lung cancer. J Nanobiotechnol. 2021;19:57. doi:10.1186/s12951-021-00804-9

72. Wei X, Liu L, Guo X, et al. Light-activated ROS-responsive nanoplatform codelivering apatinib and doxorubicin for enhanced chemo-photodynamic therapy of multidrug-resistant tumors. ACS Appl Mater Interfaces. 2018;10:17672–17684. doi:10.1021/acsami.8b04163

73. Shi X, Yang X, Liu M, et al. Chondroitin sulfate-based nanoparticles for enhanced chemo-photodynamic therapy overcoming multidrug resistance and lung metastasis of breast cancer. Carbohydr Polym. 2021;254:117459. doi:10.1016/j.carbpol.2020.117459

74. Gebrie HT, Thankachan D, Tsai HC, et al. Doxorubicin-loaded polymeric Biotin-PEG-SeSe-PBLA micelles with surface binding of biotin-mediated cancer cell targeting and redox-responsive drug release for enhanced anticancer efficacy. Colloid Surf B. 2024;241:114028. doi:10.1016/j.colsurfb.2024.114028

75. Zheng YT, Oz Y, Gu YM, et al. Rational design of polymeric micelles for targeted therapeutic delivery. Nano Today. 2024;55:102147. doi:10.1016/j.nantod.2024.102147

76. Kesharwani P, Chadar R, Sheikh A, et al. CD44-targeted nanocarrier for cancer therapy. Front Pharmacol. 2021;12:800481. doi:10.3389/fphar.2021.800481

77. Yu J, Wang L, Xie X, et al. Multifunctional nanoparticles codelivering doxorubicin and amorphous calcium carbonate preloaded with indocyanine green for enhanced chemo-photothermal cancer therapy. Int J Nanomed. 2023;18:323–337. doi:10.2147/ijn.S394896

78. Wu S, Xie X, Cheng J, et al. Enhanced solubility and anticancer efficacy of curcumin by reduction-sensitive chondroitin sulfate A-ss-deoxycholic acid micelles. Lat Am J Pharm. 2018;37:60–67.

79. Cao X, Gao T, Lv F, et al. ROS-triggered and macrophage-targeted micelles modulate mitochondria function and polarization in obesity. Nanotechnology. 2024;35. doi:10.1088/1361-6528/ad7034

80. Poursani E, Cirillo G, Curcio M, et al. Dual-responsive chondroitin sulfate self-assembling nanoparticles for combination therapy in metastatic cancer cells. Int J Pharm X. 2024;7:100235. doi:10.1016/j.ijpx.2024.100235

81. Mirhadi E, Butler AE, Kesharwani P, et al. Utilizing stimuli-responsive nanoparticles to deliver and enhance the anti-tumor effects of bilirubin. Biotechnol Adv. 2024;77:108469. doi:10.1016/j.biotechadv.2024.108469

82. Li SX, Liu X, Liang XH, et al. Dual reduction-sensitive nanomicelles for antitumor drug delivery with low toxicity to normal cells. ACS Appl Nano Mater. 2024;7:19952–19962. doi:10.1021/acsanm.4c01908

83. Yu JM, Zhang YF, Xu ML, et al. Innovative gelatin-based micelles with AS1411 aptamer targeting and reduction responsiveness for doxorubicin delivery in tumor therapy. Biomed Pharmacother. 2024;174:116446. doi:10.1016/j.biopha.2024.116446

84. Avci CB, Bagca BG, Nikanfar M, et al. Tumor microenvironment and cancer metastasis: molecular mechanisms and therapeutic implications. Front Pharmacol. 2024;15:1442888. doi:10.3389/fphar.2024.1442888

85. Zhang X, Ren X, Tang J, et al. Hyaluronic acid reduction-sensitive polymeric micelles achieving co-delivery of tumor-targeting paclitaxel/apatinib effectively reverse cancer multidrug resistance. Drug Deliv. 2020;27:825–835. doi:10.1080/10717544.2020.1770373

86. Liu M, Fu M, Yang X, et al. Paclitaxel and quercetin co-loaded functional mesoporous silica nanoparticles overcoming multidrug resistance in breast cancer. Colloid Surf B. 2020;196:111284. doi:10.1016/j.colsurfb.2020.111284

87. Gupta J, Sharma G. Nanogel: a versatile drug delivery system for the treatment of various diseases and their future perspective. Drug Deliv Transl Res. 2025;15:455–482. doi:10.1007/s13346-024-01684-w

88. Blagojevic L, Kamaly N. Nanogels: a chemically versatile drug delivery platform. Nano Today. 2025;61:102645. doi:10.1016/j.nantod.2025.102645

89. Duan Q-Y, Zhu Y-X, Jia H-R, et al. Nanogels: synthesis, properties, and recent biomedical applications. Prog Mater Sci. 2023;139:101167. doi:10.1016/j.pmatsci.2023.101167

90. Karg M, Pich A, Hellweg T, et al. Nanogels and microgels: from model colloids to applications, recent developments, and future trends. Langmuir. 2019;35:6231–6255. doi:10.1021/acs.langmuir.8b04304

91. Rajput R, Narkhede J, Naik J. Nanogels as nanocarriers for drug delivery: a review. ADMET DMPK. 2020;8:1–15. doi:10.5599/admet.724

92. Li C, Obireddy SR, Lai W-F. Preparation and use of nanogels as carriers of drugs. Drug Deliv. 2021;28:1594–1602. doi:10.1080/10717544.2021.1955042

93. Vicario-de-la-Torre M, Forcada J. The potential of stimuli-responsive nanogels in drug and active molecule delivery for targeted therapy. Gels. 2017;3:16. doi:10.3390/gels3020016

94. Radeva L, Yoncheva K. Nanogels-innovative drug carriers for overcoming biological membranes. Gels. 2025;11:124. doi:10.3390/gels11020124

95. Campea MA, Lofts A, Xu F, et al. Disulfide-cross-linked nanogel-based nanoassemblies for chemotherapeutic drug delivery. ACS Appl Mater Interfaces. 2023;15:25324–25338. doi:10.1021/acsami.3c02575

96. Setayesh A, Bagheri F, Boddohi S. Self-assembled formation of chondroitin sulfate-based micellar nanogel for curcumin delivery to breast cancer cells. Int J Biol Macromol. 2020;161:771–778. doi:10.1016/j.ijbiomac.2020.06.108

97. Gil MS, Thambi T, Phan VHG, et al. Injectable hydrogel-incorporated cancer cell-specific cisplatin releasing nanogels for targeted drug delivery. J Mater Chem B. 2017;5:7140–7152. doi:10.1039/c7tb00873b

98. Ekladious I, Colson YL, Grinstaff MW. Polymer-drug conjugate therapeutics: advances, insights and prospects. Nat Rev Drug Discov. 2019;18:273–294. doi:10.1038/s41573-018-0005-0

99. Zhao WJ, Sun KC, Yan JQ, et al. Therapeutic and responsive release mechanisms of polymer drug conjugates with diverse polymer skeletons. Nano Today. 2024;59:102526. doi:10.1016/j.nantod.2024.102526

100. Liu P, Chen N, Yan L, et al. Preparation, characterisation and in vitro and in vivo evaluation of CD44-targeted chondroitin sulphate-conjugated doxorubicin PLGA nanoparticles. Carbohydr Polym. 2019;213:17–26. doi:10.1016/j.carbpol.2019.02.084

101. Liu M, Khan AR, Ji J, et al. Crosslinked self-assembled nanoparticles for chemo-sonodynamic combination therapy favoring antitumor, antimetastasis management and immune responses. J Control Release. 2018;290:150–164. doi:10.1016/j.jconrel.2018.10.007

102. Li H, Deng C, Tan Y, et al. Chondroitin sulfate-based prodrug nanoparticles enhance photodynamic immunotherapy via Golgi apparatus targeting. Acta Biomater. 2022;146:357–369. doi:10.1016/j.actbio.2022.05.014

103. Wang H, Lin SM, Xie JC, et al. Chondroitin sulfate nanoparticles based on co-delivery dual drug induced ferroptosis in lung cancer cells by disrupting mitochondrial oxidative homeostasis. Mater Today Bio. 2025;31:101632. doi:10.1016/j.mtbio.2025.101632

104. Lu SJ, Tian HL, Li BW, et al. An ellagic acid coordinated copper-based nanoplatform for efficiently overcoming cancer chemoresistance by cuproptosis and synergistic inhibition of cancer cell stemness. Small. 2024;20:2309215. doi:10.1002/smll.202309215

105. Hu D, Pan M, Yang Y, et al. Trimodal sono/photoinduced focal therapy for localized prostate cancer: single-drug-based nanosensitizer under dual-activation. Adv Funct Mater. 2021;31:2104473. doi:10.1002/adfm.202104473

106. Li Y, Chen X, Ji J, et al. Redox-responsive nanoparticles based on chondroitin sulfate and docetaxel prodrug for tumor targeted delivery of docetaxel. Carbohydr Polym. 2021;255:117393. doi:10.1016/j.carbpol.2020.117393

107. Zhang YX, Zhou J, Wang YY, et al. Stimuli-responsive polymer-dasatinib prodrug to reprogram cancer-associated fibroblasts for boosted immunotherapy. J Control Release. 2025;381:113606. doi:10.1016/j.jconrel.2025.113606

108. Omidian H, Gill EJ, Cubeddu LX. Lipid nanoparticles in lung cancer therapy. Pharmaceutics. 2024;16:644. doi:10.3390/pharmaceutics16050644

109. Huang X, Ding Y, Gu J, et al. Organ-selective lipid nanoparticles for precise cancer therapy: beyond liposomes and polymeric micelles. Chem Eng J. 2024;494:153171. doi:10.1016/j.cej.2024.153171

110. Lechanteur A, Sanna V, Duchemin A, et al. Cationic liposomes carrying siRNA: impact of lipid composition on physicochemical properties, cytotoxicity and endosomal escape. Nanomaterials. 2018;8:1–12. doi:10.3390/nano8050270

111. Nakamura T, Yamada K, Fujiwara Y, et al. Reducing the cytotoxicity of lipid nanoparticles associated with a fusogenic cationic lipid in a natural killer cell line by introducing a polycation-based siRNA core. Mol Pharm. 2018;15:2142–2150. doi:10.1021/acs.molpharmaceut.7b01166

112. Carrasco MJ, Alishetty S, Alameh MG, et al. Ionization and structural properties of mRNA lipid nanoparticles influence expression in intramuscular and intravascular administration. Commun Biol. 2021;4:956. doi:10.1038/s42003-021-02441-2

113. Fahad M, Shah SU, Saeed MD, et al. Fabrication and evaluation of chondroitin sulfate based hydrogels loaded with chitosan nanoparticles for oral delivery of vildagliptin. Int J Biol Macromol. 2024;290:139011. doi:10.1016/j.ijbiomac.2024.139011

114. Abdelkawi A, Slim A, Zinoune Z, et al. Surface modification of metallic nanoparticles for targeting drugs. Coatings. 2023;13:1660. doi:10.3390/coatings13091660

115. Abd Elwakil MM, Mabrouk MT, Helmy MW, et al. Inhalable lactoferrin-chondroitin nanocomposites for combined delivery of doxorubicin and ellagic acid to lung carcinoma. Nanomedicine. 2018;13:2015–2035. doi:10.2217/nnm-2018-0039

116. Aly S, El-Kamel AH, Sheta E, et al. Chondroitin/lactoferrin-dual functionalized pterostilbene-solid lipid nanoparticles as targeted breast cancer therapy. Int J Pharmaceut. 2023;642:123163. doi:10.1016/j.ijpharm.2023.123163

117. Ren YX, Li PS, Xie Y, et al. Dual-responsive nanoparticles for enhanced drug delivery in breast Cancer chemotherapy. J Control Release. 2025;377:146–161. doi:10.1016/j.jconrel.2024.11.026

118. Luo K, Xu F, Yao T, et al. TPGS and chondroitin sulfate dual-modified lipid-albumin nanosystem for targeted delivery of chemotherapeutic agent against multidrug-resistant cancer. Int J Biol Macromol. 2021;183:1270–1282. doi:10.1016/j.ijbiomac.2021.05.070

119. Kim KS, Youn YS, Bae YH. Immune-triggered cancer treatment by intestinal lymphatic delivery of docetaxel-loaded nanoparticle. J Control Release. 2019;311:85–95. doi:10.1016/j.jconrel.2019.08.027

120. Du B, Zheng M, Ma H, et al. Nanozyme-natural enzymes cascade catalyze cholesterol consumption and reverse cancer multidrug resistance. J Nanobiotechnol. 2022;20:209. doi:10.1186/s12951-022-01406-9

121. Perrigue PM, Murray RA, Mielcarek A, et al. Degradation of drug delivery nanocarriers and payload release: a review of physical methods for tracing nanocarrier biological fate. Pharmaceutics. 2021;13:770. doi:10.3390/pharmaceutics13060770

122. Zhang Z, Ma L, Luo J. Chondroitin sulfate-modified liposomes for targeted co-delivery of doxorubicin and retinoic acid to suppress breast cancer lung metastasis. Pharmaceutics. 2021;13:406. doi:10.3390/pharmaceutics13030406

123. Zu M, Ma L, Zhang X, et al. Chondroitin sulfate-functionalized polymeric nanoparticles for colon cancer-targeted chemotherapy. Colloid Surf B. 2019;177:399–406. doi:10.1016/j.colsurfb.2019.02.031

124. Luo J, Gong T, Ma L. Chondroitin-modified lipid nanoparticles target the Golgi to degrade extracellular matrix for liver cancer management. Carbohydr Polym. 2020;249:116887. doi:10.1016/j.carbpol.2020.116887

125. Liu MY, Fu MF, Yang XY, et al. Paclitaxel and quercetin co-loaded functional mesoporous silica nanoparticles overcoming multidrug resistance in breast cancer. Colloid Surf B. 2020;196:111284. doi:10.1016/j.colsurfb.2020.111284

126. Arkas M, Vardavoulias M, Kythreoti G, et al. Dendritic polymers in tissue engineering: contributions of PAMAM, PPI PEG and PEI to injury restoration and bioactive scaffold evolution. Pharmaceutics. 2023;15:524. doi:10.3390/pharmaceutics15020524

127. Cook AB, Perrier S. Branched and dendritic polymer architectures: functional nanomaterials for therapeutic delivery. Adv Funct Mater. 2020;30:1901001. doi:10.1002/adfm.201901001

128. Chen W, Liu Y, Liang X, et al. Chondroitin sulfate-functionalized polyamidoamine as a tumor-targeted carrier for miR-34a delivery. Acta Biomater. 2017;57:238–250. doi:10.1016/j.actbio.2017.05.030

129. Duan Y, Xing Z, Yang J, et al. Chondroitin sulfate-functionalized polyamidoamine-mediated miR-34a delivery for inhibiting the proliferation and migration of pancreatic cancer. RSC Adv. 2016;6:70870–70876. doi:10.1039/c6ra15716e

130. O’Neil EC, Henderson M, Massaro-Giordano M, et al. Advances in dry eye disease treatment. Curr Opin Ophthalmol. 2019;30:166–178. doi:10.1097/icu.0000000000000569

131. Tovar AA, Frankel ST, Galor A, et al. Living with dry eye disease and its effects on quality of life: patient, optometrist, and ophthalmologist perspectives. Ophthalmol Ther. 2023;12:2219–2226. doi:10.1007/s40123-023-00736-7

132. Zhu R, Chen W, Gu D, et al. Chondroitin sulfate and L-cysteine conjugate modified cationic nanostructured lipid carriers: pre-corneal retention, permeability, and related studies for dry eye treatment. Int J Biol Macromol. 2023;228:624–637. doi:10.1016/j.ijbiomac.2022.12.238

133. Tan G, Li J, Song Y, et al. Phenylboronic acid-tethered chondroitin sulfate-based mucoadhesive nanostructured lipid carriers for the treatment of dry eye syndrome. Acta Biomater. 2019;99:350–362. doi:10.1016/j.actbio.2019.08.035

134. Abdullah TA, Ibrahim NJ, Warsi MH. Chondroitin sulfate-chitosan nanoparticles for ocular delivery of bromfenac sodium: improved permeation, retention, and penetration. Int J Pharm Investig. 2016;6:96–105. doi:10.4103/2230-973x.177823

135. Wang X, Majumdar S, Ma G, et al. Chondroitin sulfate-based biocompatible crosslinker restores corneal mechanics and collagen alignment. Invest Ophthalmol Vis Sci. 2017;58:3887–3895. doi:10.1167/iovs.16-21292

136. Bai Y, Chen JQ, Zhang ST, et al. Inflammation-responsive cell membrane-camouflaged nanoparticles against liver fibrosis via regulating endoplasmic reticulum stress and oxidative stress. Adv Mater. 2024;36:2310443. doi:10.1002/adma.202310443

137. Liu XZ, Fang CL, Yu HL, et al. Chondroitin sulfate-based imatinib nanoparticles targeting activated hepatic stellate cells against hepatic fibrosis. Pharmaceutics. 2025;17:351. doi:10.3390/pharmaceutics17030351

138. Zhang LF, Deng WQ, Huang QW, et al. Vicious cycle-breaking lipid nanoparticles remodeling multicellular crosstalk to reverse liver fibrosis. Adv Mater. 2024;36:2311474. doi:10.1002/adma.202311474

139. Luo J, Zhang Z, Zeng Y, et al. Co-encapsulation of collagenase type I and silibinin in chondroitin sulfate coated multilayered nanoparticles for targeted treatment of liver fibrosis. Carbohydr Polym. 2021;263:117964. doi:10.1016/j.carbpol.2021.117964

140. Tan Y, Wang Z, Guo R, et al. Dual-targeting macrophages and hepatic stellate cells by modified albumin nanoparticles for liver cirrhosis treatment. ACS Appl Mater Interfaces. 2024;16:11239–11250. doi:10.1021/acsami.3c17670

141. Li Y, Zhang T, Zhang J, et al. Dually fibronectin/CD44-mediated nanoparticles targeted disrupt the Golgi apparatus and inhibit the hedgehog signaling in activated hepatic stellate cells to alleviate liver fibrosis. Biomaterials. 2023;301:122232. doi:10.1016/j.biomaterials.2023.122232

142. Lamptey RNL, Chaulagain B, Trivedi R, et al. A review of the common neurodegenerative disorders: current therapeutic approaches and the potential role of nanotherapeutics. Int J Mol Sci. 2022;23:1851. doi:10.3390/ijms23031851

143. Wang S, Jiang Y, Yang AC, et al. The expanding burden of neurodegenerative diseases: an unmet medical and social need. Aging Dis. 2025:Inpress. doi:10.14336/ad.2024.1071

144. Tian J, Peng Q, Shen Y, et al. Chondroitin sulphate modified MoS₂ nanoenzyme with multifunctional activities for treatment of Alzheimer’s disease. Int J Biol Macromol. 2024;266:131425. doi:10.1016/j.ijbiomac.2024.131425

145. Ji D, Wu X, Li D, et al. Protective effects of chondroitin sulphate nano-selenium on a mouse model of Alzheimer’s disease. Int J Biol Macromol. 2020;154:233–245. doi:10.1016/j.ijbiomac.2020.03.079

146. Gao F, Zhao J, Liu P, et al. Preparation and in vitro evaluation of multi-target-directed selenium-chondroitin sulfate nanoparticles in protecting against the Alzheimer’s disease. Int J Biol Macromol. 2020;142:265–276. doi:10.1016/j.ijbiomac.2019.09.098

147. Feng Y, Li X, Ji D, et al. Functionalised penetrating peptide-chondroitin sulphate-gold nanoparticles: synthesis, characterization, and applications as an anti-Alzheimer’s disease drug. Int J Biol Macromol. 2023;230:123125. doi:10.1016/j.ijbiomac.2022.123125

148. Dubashynskaya NV, Bokatyi AN, Trulioff AS, et al. Delivery system for dexamethasone phosphate based on a Zn²⁺-crosslinked polyelectrolyte complex of diethylaminoethyl chitosan and chondroitin sulfate. Carbohydr Polym. 2025;348:122899. doi:10.1016/j.carbpol.2024.122899

149. Matos Oliveira I, Goncalves C, Pinheiro Oliveira E, et al. PAMAM dendrimers functionalised with an anti-TNF α antibody and chondroitin sulphate for treatment of rheumatoid arthritis. Mat Sci Eng C. 2021;121:111845. doi:10.1016/j.msec.2020.111845

150. Bishnoi M, Jain A, Singla Y, et al. Sublingual delivery of chondroitin sulfate conjugated tapentadol loaded nanovesicles for the treatment of osteoarthritis. J Liposome Res. 2021;31:30–44. doi:10.1080/08982104.2020.1730400

151. Qu X, Zhang Q, Zhang C, et al. Effect of chondroitin sulfate modified polyethyleneimine on mediating oligodeoxynucleotide YW002 in the treatment of periodontitis. RSC Adv. 2024;14:20328–20338. doi:10.1039/d4ra00884g

152. Deng CF, Xiao YB, Zhao X, et al. Sequential targeting chondroitin sulfate-bilirubin nanomedicine attenuates osteoarthritis via reprogramming lipid metabolism in M1 macrophages. Adv Sci. 2025;12:2411911. doi:10.1002/advs.202411911

153. Rehman G, Khan J, Alrashed MM, et al. Development and characterization of dual drug loaded magnetic gold nanohybrid system for osteoarthritis. J Biomater Appl. 2025;39:1222–1239. doi:10.1177/08853282251324352

154. Cesar ALA, Abrantes FA, Farah L, et al. New mesalamine polymeric conjugate for controlled release: preparation, characterization and biodistribution study. Eur J Pharm Sci. 2018;111:57–64. doi:10.1016/j.ejps.2017.09.037

155. Ma ST, Liu JB, Li YJ, et al. Egg white-derived peptides co-assembly-reinforced zein/chondroitin sulfate nanoparticles for orally colon-targeted co-delivery of quercetin in colitis mitigation. Food Biosci. 2025;65:106161. doi:10.1016/j.fbio.2025.106161

156. Wang X, Gu H, Zhang H, et al. Oral core-shell nanoparticles embedded in hydrogel microspheres for the efficient site-specific delivery of magnolol and enhanced antiulcerative colitis therapy. ACS Appl Mater Interfaces. 2021;13:33948–33961. doi:10.1021/acsami.1c09804

157. Chen Y, Shui M, Yuan Q, et al. Oral chondroitin sulfate functionalized natural polyphenol for targeted therapy of ulcerative colitis. Mater Design. 2024;238:112645. doi:10.1016/j.matdes.2024.112645

158. Gou S, Huang Y, Wan Y, et al. Multi-bioresponsive silk fibroin-based nanoparticles with on-demand cytoplasmic drug release capacity for CD44-targeted alleviation of ulcerative colitis. Biomaterials. 2019;212:39–54. doi:10.1016/j.biomaterials.2019.05.012

159. Jiang D, Xia X, He Z, et al. Biodegradable organosilica-based targeted and redox-responsive delivery system of resveratrol for efficiently alleviating ulcerative colitis. J Ind Eng Chem. 2023;123:382–395. doi:10.1016/j.jiec.2023.03.055

160. Zewail M, Nafee N, Helmy MW, et al. Coated nanostructured lipid carriers targeting the joints – An effective and safe approach for the oral management of rheumatoid arthritis. Int J Pharmaceut. 2019;567:118447. doi:10.1016/j.ijpharm.2019.118447

161. Yin XF, Wang LL, Chu XC. A novel chondroitin sulfate decorated nano platinum for the treatment of osteoarthritis. Mat Sci Eng C. 2017;78:452–456. doi:10.1016/j.msec.2017.04.028

162. He C, Yin M, Zhou H, et al. Magnetic nanoactuator-protein fiber coated hydrogel dressing for well-balanced skin wound healing and tissue regeneration. ACS Nano. 2025;19:1713–1731. doi:10.1021/acsnano.4c15647

163. Hogan KJ, Perez MR, Mikos AG. Extracellular matrix component-derived nanoparticles for drug delivery and tissue engineering. J Control Release. 2023;360:888–912. doi:10.1016/j.jconrel.2023.07.034

164. Alvarez-Chimal R, Arenas-Alatorre JA, Alvarez-Pérez MA. Nanoparticle-polymer composite scaffolds for bone tissue engineering. A review. Eur Polym J. 2024;213:113093. doi:10.1016/j.eurpolymj.2024.113093

165. Menezes R, Vincent R, Osorno L, et al. Biomaterials and tissue engineering approaches using glycosaminoglycans for tissue repair: lessons learned from the native extracellular matrix. Acta Biomater. 2023;163:210–227. doi:10.1016/j.actbio.2022.09.064

166. Coburn JM, Gibson M, Monagle S, et al. Bioinspired nanofibers support chondrogenesis for articular cartilage repair. PNAS. 2012;109:10012–10017. doi:10.1073/pnas.1121605109

167. Chen S, Chen W, Chen Y, et al. Chondroitin sulfate modified 3D porous electrospun nanofiber scaffolds promote cartilage regeneration. Mat Sci Eng C. 2021;118:111312. doi:10.1016/j.msec.2020.111312

168. Sharma S, Swetha KL, Roy A. Chitosan-chondroitin sulfate based polyelectrolyte complex for effective management of chronic wounds. Int J Biol Macromol. 2019;132:97–108. doi:10.1016/j.ijbiomac.2019.03.186

169. Place LW, Sekyi M, Kipper MJ. Aggrecan-mimetic, glycosaminoglycan-containing nanoparticles for growth factor stabilization and delivery. Biomacromolecules. 2014;15:680–689. doi:10.1021/bm401736c

170. Noh HJ, Kim HS, Cho S, et al. Melamine nanosensing with chondroitin sulfate-reduced gold nanoparticles. J Nanosci Nanotechnol. 2013;13:8229–8238. doi:10.1166/jnn.2013.7926

171. Santos PRM, Johny A, Silva CQ, et al. Improved metal cation optosensing membranes through the incorporation of sulphated polysaccharides. Molecules. 2022;27:5026. doi:10.3390/molecules27155026

172. Xu K, Yang J, Shen L, et al. An antifouling electrochemical biosensor based on chondroitin sulfate-functionalized polyaniline and DNA-peptide conjugates for cortisol determination in body fluids. Mikrochim Acta. 2023;190:494. doi:10.1007/s00604-023-06083-5

173. Zhao S, Zhou Y, Wei L, et al. Low fouling strategy of electrochemical biosensor based on chondroitin sulfate functionalized gold magnetic particle for voltammetric determination of mycoplasma ovipneumonia in whole serum. Anal Chim Acta. 2020;1126:91–99. doi:10.1016/j.aca.2020.06.015

174. Kalita M, Joice A, Le KD, et al. Preparation of nanosensors for detecting the activity of glycosaminoglycan cleaving enzymes. Methods Mol Biol. 2022;2303:687–694. doi:10.1007/978-1-0716-1398-6_52

Inverex EV has announced a new financing plan for its compact electric vehicle, the Inverex XIO, offering buyers the chance to purchase the car for an initial payment of Rs. 1,500,000. The remainder can be paid through monthly installments at 0% markup.

This new offer aims to lower the barrier to entry for Pakistani consumers considering electric vehicles. With increasing fuel costs and growing interest in sustainable transport, Inverex’s XIO comes as a practical and cost-effective urban car.

Vehicle Overview

The Inverex XIO is a compact 5-door electric hatchback suitable for city driving. While complete specifications have not been published by the company on the flyer, previously shared details indicate the car includes:

• Compact design optimized for urban traffic
• Fully electric drivetrain
• Home and commercial charging compatibility
• Low running and maintenance costs

Inverex markets the XIO as a smart solution for daily commuting, with the added benefit of zero emissions.

Installment and Booking Details

Under the new financing plan:

• Down payment: Rs. 1,500,000
• Remaining balance: Payable in easy monthly installments
• Markup: 0%
• Contact: 111-11-EV-EV (38-38) or visit inverexev.com

The offer is valid nationwide through authorized Inverex EV dealers and service partners.

Immigration, Refugees and Citizenship Canada (IRCC) has increased the minimum settlement fund requirement for those immigrating through the Rural Community Immigration Pilot (RCIP) and the Francophone Community Immigration Pilot (FCIP).

As of July 29, 2025, foreign nationals need a minimum of $2,544 more in settlement funds to immigrate through the RCIP or the FCIP.

Assess your eligibility for the RCIP

For a family of one, the minimum funds required to qualify for the RCIP or the FCIP increased from $7,963 to $10,507 on July 29 – a 31.94% increase.

The RCIP and the FCIP are employer-driven pathways to permanent residence in Canada for those looking to settle in rural or francophone communities outside Quebec.

How much money do I need to immigrate to Canada through the RCIP or the FCIP?

The minimum amount of funds needed to immigrate through the RCIP or the FCIP depends on the size of your family.

Both programs share the same settlement funds requirements.

Number of family members	Funds required (CAD) from July 29, 2025	Previous minimum fund requirement
1	$10,507	$7,963
2	$13,080	$9,692
3	$16,080	$12,069
4	$19,524	$15,056
5	$22,143	$17,145
6	$24,975	$19,015
7	$27,806	$20,884
For each additional member over 7	$2,831	$1,869

How do I calculate the size of my family?

Your family size includes

• Yourself;
• Your spouse or common-law partner; and
• Dependent children (yours, your spouse or common law partner’s).

You must include a spouse or common-law partner and dependent children even if they are Canadian citizens or permanent residents, and/or even if they are not coming to Canada with you.

What does IRCC accept as proof of funds?

Proof of funds can be any one of the following documents:

• bank account statements;
• bank drafts;
• cheques; or
• money orders.

The money needs to be available when applying for the program, and when you are issued your permanent resident visa.

About the RCIP and the FCIP

The RCIP and the FCIP launched earlier this year to help employers in rural communities outside Quebec address labour shortages.

To be eligible, a foreign national must have a job offer from a designated employer in the region. This offer must also be endorsed by a local economic development organization.

Besides that, the foreign national has to meet certain eligibility criteria regarding education, work experience, language proficiency, and settlement funds. For the FCIP, foreign nationals need to prove French language proficiency.

Those who meet all the eligibility criteria can apply directly to the federal government for PR.

They are also eligible to apply for a work permit so they can start working for their employer while their PR application is being processed.

There are 14 communities in total participating in the RCIP, while there are six communities participating in the FCIP. Each community has selected specific priority sectors and occupations based on their economic goals and workforce needs.

Assess your eligibility for the RCIP

 

CNN
 — 

When you think of Tokyo, you might think of neon-lit skyscrapers and its world-famous bullet train system, or films like “Akira” and “Ghost in the Shell” that depict a futuristic Japan filled with intelligent robots and holograms.

But there’s a more mundane side of Japan that you won’t find anywhere in these cyberpunk films. It involves fax machines, floppy disks and personalized ink stamps – relics that have long died out in other advanced nations but have stubbornly persisted in Japan.

For everyday residents, the lag in digital technology and the ensuing bureaucracy is at best inconvenient, and at worst makes you want to tear your hair out.

“Japanese banks are portals to hell,” one Facebook user wrote in a local expat group. A commenter joked sarcastically: “Maybe sending a fax would help.”

The scale of the problem became terrifyingly clear during the Covid-19 pandemic, as the Japanese government struggled to respond to a nationwide crisis with clumsy digital tools.

In the years since, they’ve launched a dedicated effort to close that gap, including a newly created Digital Agency and a host of new initiatives. But they’re arriving to the tech race decades late – 36 years after the arrival of the World Wide Web, and more than half a century after the first ever email was sent.

Now as the country races to transform itself, the question remains: What took them so long, and can they still catch up?

It wasn’t always this way. Japan was the object of global admiration in the 1970s and ‘80s, when companies like Sony, Toyota, Panasonic and Nintendo became household names. Japan brought the world beloved devices like the Walkman, and games like Donkey Kong and Mario Bros.

But that changed by the turn of the century with the rise of computers and the internet.

While the world was shifting to software-driven economies, “Japan, with its strengths in hardware, was slow to adapt to software and services,” said Daisuke Kawai, director of the University of Tokyo’s Economic Security and Policy Innovation Program.

A range of factors exacerbated the problem, he said. Japan didn’t invest enough in information and communications technology, and as its electronics industry shrank, Japanese engineers flocked to foreign companies.

That left a government with low digital literacy and a lack of skilled tech workers. Over time, different ministries and agencies adopted their own patchwork IT strategies, but there was never a unified government push – meaning public services never properly modernized and remained reliant on paper documents and hand-carved, personalized seals called hanko that are used for identity verification.

There were cultural factors, too.

“Japanese companies are known for their risk-averse culture, seniority-based … hierarchical system, and a slow, consensus-driven decision-making process – all of which hampered innovation,” Kawai said.

And thanks to Japan’s plummeting birthrate, it has far more old people than young people. This outsized elderly proportion meant a wider distrust of new technologies, wariness of digital fraud, a preference for traditional methods like the hanko, and “relatively little demand or pressure for digital services,” Kawai said.

That apathy was widespread, said Jonathan Coopersmith, professor emeritus of history at Texas A&M University. Small businesses and individuals didn’t feel compelled to switch from fax machines to computers: Why buy expensive new machinery and learn how to use it, when fax worked fine and everybody in Japan used it anyway?

Larger corporations and institutions like banks or hospitals found a potential switch too disruptive to daily services. “The bigger you are, the harder it is to change, especially software,” said Coopersmith, who wrote about Japan’s relationship with the fax machine in a 2015 book about the device.

It also posed a legal headache. Any new technology requires new laws – for instance, how electric scooters prompted new road regulations, or how countries worldwide are now trying to legislate against deepfakes and AI copyright after the AI boom. Digitizing Japan would have required changing thousands of regulations, Coopersmith estimates – and lawmakers simply had no incentive to do so. After all, it’s not like digitization is a key issue driving votes in elections.

He summed it up: “Why do I want to become part of the digital world if I don’t need to?”

The pandemic push

The result was that for decades, Japan remained stuck with old tech even as it progressed in other ways – creating the ultimate contradiction.

Japan has world-class robotics and aerospace industries, and features of day-to-day life that tend to awe foreign tourists, like safe and clean public spaces, ubiquitous vending machines and convenience stores, widely accessible public transit and a comprehensive bullet train system.

Its digital failings look even more stark by comparison.

In 2018, Japan’s then cybersecurity minister sparked outrage and disbelief when he claimed he’d never used a computer since his secretaries did “that kind of thing” – before walking back his remarks a few days later.

And it wasn’t until 2019 that the last company in Japan still operating pagers finally halted services – decades after the personal messaging device was rendered obsolete by cell phones.

The prevalence of old technology also created endless bureaucracy. Opening a bank account or registering for housing might require a hanko seal, along with documents of personal information you have to visit a local council to request in person, said Kawai.

In the end, it took a global pandemic to finally force change. Japan’s technological gap became evident as national and local authorities became overwhelmed, without the digital tools to streamline their processes.

It was only in May 2020, months after the virus began running rampant globally, that Japan’s health ministry launched an online portal for hospitals to report cases instead of relying on handwritten faxes, phone calls or emails.

And even then, hiccups persisted. A contact tracing app had a months-long system error that failed to notify people of possible exposure, reported public broadcaster NHK. Adjusting to remote work and school was tough, as many had never used file-sharing services or video tools like Zoom.

In one mind-boggling case in 2022, a Japanese town accidentally wired the entirety of its Covid relief fund – about 46.3 million yen ($322,000) – to just one man’s bank account. The confusion stemmed from the bank being given both a floppy disk of information and a paper request form – but by the time authorities realized their error, the man had already gambled away most of the funds, according to NHK.

For anyone under 35, a floppy disk is a magnetic memory strip encased in plastic that is physically inserted into a computer. Each one typically stores up to 1.44MB of data – less than an average-resolution photo on your iPhone.

The situation got so bad that at one point, Takuya Hirai – who in 2021 was appointed to the newly created role of Minister of Digital Transformation – described the country’s handling of the pandemic as a “digital defeat.”

Thus, the Digital Agency was born – a department tasked with bringing Japan up to speed, born from a “combination of fear and opportunity,” said Coopersmith.

Created in 2021, it launched a series of initiatives including rolling out a smart version of Japan’s social security card and pushing for more cloud-based infrastructure.

Last July, the Digital Agency finally declared victory in its “war on floppy disks,” eliminating the disks across all government systems – a mammoth effort that required scrapping more than 1,000 regulations governing their use.

But there were growing pains, too. At one point, the government asked the public for their thoughts about the metaverse – through a convoluted system that required downloading an Excel spreadsheet, filling out your details, and emailing the document back to the ministry, local media reported.

After the move garnered scorn and disbelief on social media, then Digital Minister Taro Kono wrote on Twitter: “The (ministry) will respond properly using an (online) form from now on.”

With the government firmly forging forward, companies hastened to follow, many hiring external contractors and consultants to help overhaul their systems, said Kawai.

Masahiro Goto is one such consultant. As part of the Nomura Research Institute’s (NRI) digital transformation team, he has helped large Japanese companies across all industries adapt to the digital world – from designing new business models to adopting new internal systems.

These clients are often “eager to move forward, but they’re unsure how to go about it,” he told CNN. “Many are still using old systems that require a lot of maintenance, or systems that are approaching end-of-service life. In many cases, that’s when they reach out to us for help.”

The NRI consultants are in high demand – the number of companies reaching out for their services “has definitely been rising year by year,” especially in the last five years, Goto said. And for good reason: for years, Japanese companies outsourced their IT needs, meaning they now lack the in-house skills to fully digitize.

“Fundamentally, they want to make their operations more efficient, and I believe they want to actively adopt digital technologies as a means of survival,” he said. “After all, Japan’s population is going to continue to decline, so improving productivity is essential.”

There may be resistance in certain pockets – the Digital Agency’s plan to eliminate fax machines within the government received 400 formal objections from different ministries in 2021, according to local media.

Things like the hanko seal – which are rooted in tradition and custom, and which some parents gift to their children when they come of age – may be harder to phase out given their cultural significance.

The pace of progress also depends on how willing the Digital Agency is to push regulatory reform, and how much lawmakers will prioritize digitization in creating future budgets, Kawai said. There’s also the fact Japan is playing catch-up with moving goalposts, as new technologies surge forward in other parts of the world.

“This is going to be an ongoing challenge because the digital technologies of 2025 are going to be different from the ones of 2030, 2035,” said Coopersmith.

But experts are optimistic. Kawai estimates at this rate, Japan could catch up with some Western peers in five to 10 years.

And finally, there’s a public hunger for it, with more and more businesses accepting cashless payments and rolling out new online services.

“People are generally eager to digitize for sure,” said Kawai. “I’m sure that young people, or the general public, prefer to digitize as fast as possible.”