A thermosensitive material coated resonant stent for drug delivery on demand

Abstract

An electromagnetic energy source in the radio-frequency range delivers power to a stent circuit via resonant inductive coupling, allowing a thermally triggered release of gel via Joule heating. A gold-electroplated, medical-grade stainless steel stent, serving as the base of the prototype device, melts a coating made from an emulsion composed mainly of dodecanoic acid. These coated devices produce wirelessly controllable releases of a gel into thermally regulated, stirred water that is near body temperature. The gel is made from salt, water, and gelatine from porcine skin and used to simulate drug release in this study. Thus, this system serves as a proof of concept to show the viability of controlling local drug delivery using this prototype device. Dodecanoic acid, a fatty acid, has a phase transition from solid to liquid near 43∘C and has relatively good biocompatibility. The average melting temperature of two different emulsions was 40.8±0.7∘C, a suitable value for the targeted application. Demonstration of controllable releases used electromagnetic pulses of approximately 180 seconds in duration, illustrating reproducibility of a controllable release phase while remaining relatively inert in the absence of stimuli. Releases were observable through measuring the conductivity of the water, the water temperature, and the stent temperature. This electrothermally active stent device enables wirelessly controlled local delivery with controlled dosage and timing, a concept with a wide range of potential applications. Some relevant examples include inhibiting restenosis or cancer treatment via targeted chemotherapy.