Electrical analysis of minocycline eluting layer-by-layer thin-films from functional micro-electrode arrays

Although the potential for intracortical implanted microelectrodes has been demonstrated, successful clinical translation has been hindered by their inability to function over clinically relevant time-points (years to decades). Failure of implanted microelectrode arrays (MEA's) has been highly correlated with the foreign body response which progressively encapsulates the MEA's in a glial sheath, isolating them from the surrounding microenvironment. To mitigate this response, drug delivery has been implemented to release therapeutics from the device surface. This has allowed limited success at acute time points; however, challenges in maintaining longterm therapeutic dosages has resulted in an inability to mitigate chronic inflammation. A recent publication has demonstrated the use of multi-layer film composed of dextran-sulfate, minocycline hydrochloride (MH), and gelatin type A, assembled via layer-by-layer technology, capable of providing sustained release of MH for several weeks; however, their impact on functionality has not yet been analyzed. We found that after being coated with 20 layers NeuroNexus devices exhibited significantly increased impedance at 100Hz, 1kHz, and 10kHz, though this was significantly reduced after 24-hours of incubation in PBS. Charge carrying capacity also significantly increased after incubation in PBS. It can be concluded that these coatings do influence MEA's immediately after coating, but is less impactful over time as the coating degrades.