Multifunctional Fluorinated Coating for Improving Neural Implant Biocompatibility

Although implantable neural electrode devices have been used in animals and human for neuroscience research and clinical applications, they face the challenge of signal degradation due to a myriad of reasons including implantation trauma, glial scarring, biofouling, and loss of signal-generating neurons. During implantation, the neural probe inflicts injury to the brain tissue by breaking blood vessels and inducing mechanical stress to the surrounding tissue. The implantation then triggers a cascade of immune response involving non-specific protein adsorption, inflammatory cell adhesion followed by the encapsulation of the probe by glial sheath. The disrupted blood flood may cause hypoxia, which along with the trauma and inflammation may compromise neuronal survival and function.<br/>Here, we used chemically and biologically inert perfluorocarbon (PFC) as a multi-functional coating for implantable neural interfaces providing 1) lubrication during insertion to reduce insertion trauma, 2) anti-fouling surface, and 3) oxygen supply to the injury site. Preliminary data shows that the PFC coating can reduce peak insertion force of a single-shank silicon probe by at least 50%, translating to less acute trauma. The PFC coating also effectively decrease non-specific protein adsorption and inflammatory cell attachment. In addition, the same coating is capable of carrying oxygen and passively releasing it over at least six hours. We also studied the effect of the coating on the interfacial impedance of platinum electrodes and found no significant difference in impedance between the bare and PFC coated electrodes. Combined, these functionalities of the PFC coating showed great potential for reducing implantation trauma and improving neuronal survival near the neural electrode implants.