Design and Near-Infrared Actuation of a Gold Nanorod⁻Polymer Microelectromechanical Device for On-Demand Drug Delivery

Polymeric drug delivery systems usually deliver drugs by diffusion with an initial burst of release followed by a slower prolonged release phase. An optimal system would release exact doses of drugs using an on-demand external actuation system. The purpose of this study was to design and characterize a novel drug-delivery device that utilizes near infrared (NIR 800 nm) laser-actuated drug release. The device was constructed from biocompatible polymers comprising a reservoir of drug covered by an elastic perforated diaphragm composed of a bilayer of two polymers with different thermal expansion coefficients (ethylenevinylacetate (EVA) and polydimethylsiloxane (PDMS) containing gold nanoparticles). Upon illumination with a NIR laser, the gold nanoparticles rapidly heated the bilayer resulting in bending and a drug-pumping action through the perforated bilayer, following sequential laser-actuation cycles. Devices filled with the anti-proliferative drug docetaxel were seen to release only small amounts of drug by diffusion but to release large and reproducible amounts of drug over 20 s laser-actuation periods. Because NIR 800 nm is tissue-penetrating without heating tissue, suitable geometry drug-delivery devices might be implanted in the body to be actuated by an externally applied NIR laser to allow for on-demand exact drug dosing in vivo.