Local Drug Delivery System For Dynamic Control Of Neural Environment Using Parylene-Based Microelectrodes

Delivering drugs directly and locally to the brain tissue opens new approaches to disease treatment and improving neural interfaces. Several approaches using neural prostheses have been made to deliver drugs by bypassing the blood-brain barrier (BBB). In this study, we propose a new local drug delivery system for dynamic control of the neural environment using parylene-based microelectrodes. This polymer-based flexible microelectrode has both drug delivery and electrophysiological recording capabilities in a single probe. An in vitro model using cells found in the chronic neural probe environment provides control of independent variables and thus a useful environment to test the efficacy of delivered drugs. The in vitro model uses a combination of meningeal fibroblasts, microglia and astrocytes plated directly on the microelectrode sites. The drug delivery system utilizes two different drug delivery strategies: (1) a liquid phase drug delivery for water soluble drugs via an integrated microfluidic port, and (2) drug-embedded nanoparticle-mediated delivery for water insoluble drugs pre-loaded into a passive microfluidic port. We are currently characterizing the effects of dexamethasone (DEX) delivery on cell development using impedance spectroscopy and fluorescence microscopy. Early results show that electrode sites with plated cells on functional probes increase the impedance. This local drug delivery system provides an efficient testing protocol for therapeutic drugs intended to improve the neural interface.