An implantable piezoelectric polymer nanofiber device that releases controlled amounts of a drug under mechanical force. (Credit: Jin Nam/UCR)

A membrane made from threads of a polymer commonly used in vascular sutures can be loaded with therapeutic drugs and implanted in the body, where mechanical forces activate the polymer’s electric potential and slowly release the drugs. The novel system overcomes the biggest limitations of conventional drug administration and some controlled release methods.

The system uses poly(vinylidene fluoride-trifluro-ethylene), or P(VDF-TrFE), which produces an electrical charge under mechanical stress. Structuring the material in nanoscale by electrospinning optimized the sensitivity of the resulting nanofibers so the drug-delivery system would respond to physiologically safe magnitudes of force while remaining insensitive to daily activities. The large surface area of the nanofibers allowed them to adsorb a relatively large quantity of drug molecules.

After embedding the film in a hydrogel that mimics living tissue, a series of tests using therapeutic shockwaves generated enough electric charge to release an electrostatically attached model drug molecule into the surrounding gel. The researchers could tune the drug release quantity by varying the applied pressure and duration.