Formation of microcapsules by ultrasound stimulation for use in remote-controlled drug-eluting stents.

Coronary Heart Disease (CHD) is the leading cause of death globally. The placement of drug-eluting stents (DESs) in diseased coronary arteries is the most successful minimally-invasive intervention to treat CHD. The key limitations of such interventional therapy are the risk of in-stent restenosis (ISR) and late stent thrombosis. This paper investigates a new drug-release system by formatting nanoparticles as drug carriers, which are later subjected to an external ultrasonic stimulus for controlled drug release remotely for DESs. The drug delivery could delay smooth muscle cell growth whilst enabling effective regeneration of a functional endothelium. Microcapsules were produced by employing a layer-by-layer technique, encapsulated with Rhodamine 6G dye used in place of anti-restenotic drugs. Gold nanoparticles were employed as a shell in the microcapsules. The presence of gold nanoparticles significantly enhanced the efficiency of the ultrasonically induced dye release from the microcapsules and increased the sensitivity of the microcapsules to ultrasonic stimulation compared to those without gold nanoparticles.