Sprout-Inspired Polypyrrole-Integrated Electrodes for Reduced Impedance and Enhanced Biological Compatibility

Abstract

Creating coatings on the electrode surface is a promising strategy to isolate the electrode surface from biological contamination and minimise the interference of foreign body reactions. However, this can also lead to an increase in the impedance of the implant, thereby affecting its working performance. In this paper, through electrochemical oxidation, polypyrrole is grown between the sulfobetaine methacrylate coating and the electrode in a manner similar to seed germination. The modified electrode (CE) not only shows lower impedance and higher capacitance than bare electrode, but also resistants to the adhesion of proteins, bacteria, and fibroblasts. In vivo animal experiments demonstrate that CE leads to milder inflammation and fibrous encapsulation. In vitro analogue signal monitoring experiments further demonstrated the potential of CE as a long-term implantable bioelectrode. In addition, the unique way in which conductive substances grow on SBMA coatings is a new discovery that may help research in other subject areas.

Keywords: Zwitterionic, Bioelectrode, Immune response, Polypyrrole, Impedance