Control system closed loop

North Carolina researchers have developed a smart skin patch designed to monitor a patient’s blood and release a blood-thinning drug, as needed, to prevent thrombosis (dangerous blood clots).

Thrombosis — one of the leading causes of cardiovascular mortalities and morbidities worldwide — occurs when blood clots disrupt the normal flow of blood in the body, which can cause severe health problems such as pulmonary embolism, heart attack, or stroke.

Current treatments often rely on the use of blood thinners, such as heparin, requiring patients to test their blood on a regular basis to ensure proper dosages. Dosage is iffy; too large a dose can cause problems such as spontaneous hemorrhaging, while doses that are too small may not prevent thrombosis.

So researchers at North Carolina State University and the University of North Carolina at Chapel Hill developed a feedback-controlled anti-coagulant smart skin patch to release just the needed level of heparin.

The patch incorporates an array of painless microneedles made of a material that is responsive to thrombin (an enzyme that initiates clotting in the blood). When elevated levels of thrombin enzymes in the bloodstream come into contact with the microneedle, the enzymes cause the thrombin-responsive material in the microneedles to release the right amount (and no more) of blood-thining heparin into the bloodstream to prevent blood clots.*

The patch was successfully tested in a mouse model.

“Our goal was to generate a patch that can monitor a patient’s blood and release additional drugs when necessary — effectively, a self-regulating system, ” says Zhen Gu, co-corresponding author on a paper published Nov. 25, 2016 in Advanced Materials describing the work. Gu is an associate professor in the joint biomedical engineering program at NC State and UNC.

“This paper represents a good first step, and we’re now looking for funding to perform additional preclinical testing, ” Gu said.

The work was supported by the Alfred P. Sloan Foundation, NIH’s Clinical and Translational Science Awards, and the National Science Foundation.

* Closed-loop heparin delivery system

Abstract of Thrombin-Responsive Transcutaneous Patch for Auto-Anticoagulant Regulation