People with diabetes need to check their blood glucose multiple times a day. It’s not uncommon for patients with diabetes to monitor glucose levels at least five times a day. Discrete, on-demand testing requires pricking your finger for a blood sample or inserting a microfilament sensor in the body for continuous glucose monitoring.
The daily routine of glucose testing is often a major inconvenience for most people with diabetes, and there are always risks, said Makarand Paranjape, an associate professor of physics and director of the Georgetown Nanoscience and Microfabrication Cleanroom Lab (GNuLab) in the College of Arts & Sciences.
“You’re inserting a needle into your arm or abdomen and putting a sensor inside the body to detect blood glucose. Anytime you put something in your body, it’s going to be attacked by your own immune system,” Paranjape said.
Paranjape hopes to decrease those risks with his new non-invasive technology, a transdermal patch that can detect biomarkers typically found in the bloodstream without drawing blood or inserting any device into the body.
What started as a project initially funded by the Department of Defense 25 years ago has since become one of Paranjape’s passionate pursuits. Over the last two decades, the physics professor has refined his biomedical technology and developed a family of patents through Georgetown’s Office of Technology Commercialization that he hopes will positively impact the quality of life for patients suffering from a wide variety of chronic disease conditions.
A Better Way to Detect Biomarkers
Blood tests help detect biomarkers that physicians use to treat patients, from diabetes to heart disease and even some forms of cancer.
While these biomarkers exist in the bloodstream, they also permeate through the capillaries and into the liquid surrounding cells in body tissue known as interstitial fluid. Detecting biomarkers in this fluid is even easier than in the blood because the larger components of blood, like platelets, white and red blood cells, can’t pass through the natural filtration mechanism provided by capillaries.
“The interstitial fluid, sometimes also called extracellular fluid, bathes every living cell in your body,” Paranjape said. “It’s like a pre-filtered sample. When you draw blood, you have to filter down all the other stuff you don’t need. We don’t have to do that, so the interstitial fluid is ideal for detecting blood-borne biomarkers or biomolecules.”
Paranjape engineered a patch that non-invasively samples interstitial fluid.
Paranjape says his invention is akin to a Band-Aid. Each patch contains an array of microheaters, each of which is about the diameter of a single strand of human hair. For just a few milliseconds, these microheaters reach 100 degrees Celsius to create a temporary micropore in only the top-most layer of skin to access and collect interstitial fluid.
“That highly-controlled thermal pulse effectively removes only a microscopic portion of the top-most layer of dead skin. It’s essentially exfoliating that small area of skin to an extent that you’re creating a hair-sized micropore from the top of the skin extending to the living tissue,” he said. “Once you get through that layer, there is plenty of interstitial fluid that actually comes up and out of the micropore since your heartbeat is providing pressure.”
Whereas existing solutions that sample interstitial fluid require a sensor inserted into the body, Paranjape’s device allows the interstitial fluid to exude naturally from the pores after the microheaters activate, making it noninvasive. His device is also pain-free, verified in a pilot clinical trial, since the temperatures applied and micropores generated are both shallow and don’t reach the skin’s nerve endings.
It will also require less maintenance from patients. Whereas some patients with diabetes may not monitor their blood glucose enough during the day because they forget or are apprehensive of the pain from a pinprick, the patch can potentially monitor biomarkers on its own, Paranjape said. Patients would only have to change the patch once a day.
While Paranjape has primarily developed the patch in the context of diabetes, he’s testing his patch to draw biomarkers for other disease conditions, such as traumatic brain injury.
Transforming Drug Delivery
Paranjape is now working on the next step of his biomedical patch: drug delivery.
Transdermal patches that deliver drugs already exist, such as nicotine patches that people use to wean themselves off of smoking. However, current patches are less efficient because they require existing drugs to be modified, Paranjape said.
“Most of these patches require the drug in question to be tailored chemically to allow it to penetrate through intact skin. Ours does not,” he said. “We can use off-the-shelf drugs. We are creating tiny pores through the skin so the drug can easily enter and diffuse to the circulatory system.”
Paranjape’s lab is experimenting with loading drugs into his patch that can be administered after the microheaters activate. The patch could also allow patients to schedule release times and determine the correct dosing.
Paranjape also said his patch is promising because transdermal drug delivery could reduce the dosages patients need and reduce medical waste.