Voltage-Gated Closed-Loop Control of Small-Molecule Release from Alumina-Coated Nanoporous Gold Thin Film Electrodes

Precise timing and dosing of potent small-molecule drugs carries significant potential for effective pharmaceutical management of disorders that exhibit time-varying therapeutic windows such as epilepsy. This study demonstrates the use of alumina-coated nanoporous gold (np-Au) thin film electrodes for iontophoretic release of fluorescein as a small-molecule drug surrogate with picogram dosing and a few seconds temporal resolution. A custom microfluidic platform is engineered to trigger molecular release from an integrated np-Au chip and monitor the resulting time-varying fluorescein concentration. Following a systematic study of the influence of applied voltage on loading capacity and release kinetics, a LabVIEW-based closed-loop control interface is employed to demonstrate voltage-gated fluorescein release with preprogrammed arbitrary concentrations waveforms.