Biocompatible dipeptide coated on Pt/PEDOT:PSS modified silicon probes for tissues rejection alleviation

The implantable neural probe is an indispensable tool to record the high-quality spike signals. However, the high interface impedance of electrode-tissue and severe tissue rejection degrade the signal quality and shorten the service life of neural probes in-vivo. Here, a Pt/PEDOT:PSS modified silicon probes with biocompatible dipeptide layer is proposed to avoid these issues. First, a bilayer Pt/PEDOT:PSS was electrochemically deposited on gold microelectrodes to reduce the impedance. Then, a layer of dipeptide was deposited on the modified probe by physical vapor deposition (PVD) to mitigate tissue rejection. The electrochemical results show that the electrode-tissue interface impedance can be reduced by two orders of magnitude by the Pt/PEDOT:PSS modification, with negligible impedance variation by the following dipeptide layer. From the in-vitro accelerated aging, it can be inferred that the Pt/PEDOT:PSS/dipeptide modified microelectrodes can survive for more than 10 weeks. In-vitro cytotoxicity experiments show that the dipeptide can help improve the biocompatibility. Lastly, in-vivo implantation further proves that dipeptide may contribute to the realization of lower tissues rejection and higher signal-to-noise ratio within 8 weeks of implantation. The widely used silicon neural probes with the Pt/PEDOT:PSS modification and overall dipeptide coating provide as a new solution for long-term biocompatibility and high-quality neural signals.