In vivo inflammatory and wound healing effects of gold electrode voltammetry for MEMS micro-reservoir drug delivery device

The in vivo biocompatibility and biofouling of gold electrodes for a microelectromechanical systems drug delivery device were investigated in a rodent model. The role of the applied voltage and gold electrolysis products in modulating the inflammatory response (biocompatibility), and the temporal adhesion of cellular populations onto macroscopic gold film electrodes (biofouling) were analyzed in reference to two controls, devices to which voltage was not applied (uncorroded) or voltage was applied to inert platinum electrodes (electrical controls). Voltammetry was applied to the gold surfaces once (day 4, 7, 14, 21, 28, 35, 42, or 49), while voltage of identical magnitude was applied to the electrical controls. An inflammatory response characterized by a rapid decrease of leukocyte concentration to control levels was observed 48 h following voltage application with no significant cell concentration difference (p>0.05) between the corroded devices and electrical controls. The histological evaluation of the direct implant fibrous capsule showed comparable thickness of voltage applied and control specimens. The gold corrosion peak current showed no significant difference (p>0.05) among peak values at all time points. It was concluded that gold electrode corrosion was biocompatible and its electrochemical performance was not hindered by fibrous capsule formation.