A smart patch designed by researchers from North Carolina State University and the University of North Carolina at Chapel Hill prevents thrombosis, the occurrence of dangerous blood clots. Microneedles covering the patch are composed of a polymer that includes hyaluronic acid (HA) and the blood-thinning drug Heparin.

The polymer has been modified to be responsive to thrombin, an enzyme that initiates clotting in the blood.

The microneedle patch is made of heparin-modified hyaluronic acid. Image courtesy of Yuqi ZhangThe microneedle patch is made of heparin-modified hyaluronic acid. Image courtesy of Yuqi ZhangWhen the microneedles are exposed to elevated levels of thrombin enzymes in the bloodstream, the enzymes break the specific amino acid chains that bind the Heparin to the HA, releasing the drug. The amount of Heparin released by the disposable, self-regulating patch is determined by the thrombin levels in the patient’s blood.

In mouse model experiments, animals were injected with large doses of thrombin, which would result in fatal blood clotting of the lungs if left untreated. In the first test, mice were left untreated, given a shot of Heparin, or given the smart patch, and injected with thrombin 10 minutes later.

Fifteen minutes after the thrombin injection, only the mice who received no treatment died. In a second experiment, thrombin was injected six hours after treatment. Fifteen minutes after the thrombin injection, all of the mice with the smart patch were fine, but around 80% of the mice that received the Heparin shot had died.

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