Antimicrobial coated intracortical probes reduce invading microbe abundance and subsequent neuroinflammation

Intracortical microelectrodes allow for the recording of neural signals in the brain but show decreased recording performance over time. This failure is due primarily to the neuroinflammatory response triggered by microelectrode implantation. We have shown that one consequence of the disruption of the blood-brain barrier following microelectrode probe implantation is the invasion of non-native bacteria to the implant site, which exacerbates the neuroinflammatory response. This study investigates the effects of coating non-functional silicon intracortical microelectrodes with an antimicrobial titania nanotube array (TNA) to reduce the relative abundance of invasive microbes and the resulting neuroinflammatory response. TNA-coated probes were implanted into mice for either 4 weeks (N = 4) or 12 weeks (N = 4) and compared to uncoated probes at both time points. We found that the TNA coatings reduce microbe relative abundance at both acute and chronic time points, correlating with fewer significantly expressed neuroinflammatory markers. Coating probes with TNAs allows for the beneficial effects of the antimicrobial coating to persist to chronic time points, in contrast to the detrimental effects of chronic systemic antibiotic administration reported previously. This study establishes antimicrobial TNA coatings as a platform for controlling the microbial environment, reducing invasive bacteria and neuroinflammation at the implant site. By mitigating the neuroinflammatory response, TNA-coated probes address one of the key contributors to intracortical microelectrode failure, thereby providing a strong platform that may support improved chronic recording performance in future functional intracortical microelectrode applications.