Biofunctional conducting polymers: synthetic advances, challenges, and perspectives towards their use in implantable bioelectronic devices

Conducting polymers (CPs) are organic semiconductors that have gained popularity in more recent years as components of bioelectronic devices designed to electrically communicate with biological environments. Synergy between the material and biological tissue, both on a structural and functional level, is paramount for the proper performance of an implantable biomedical device. As such, significant progress has been made on understanding the fundamental impact of the molecular and macro structure of CPs on their functional properties such as conductivity and charge mobility. At the same time, the development of a variety of synthetic approaches has yielded a library of CPs with improved mechanical and electronic properties. Specifically, chemical biofunctionalization of CP films has significantly decreased the foreign body response, the main contributor to device failure. Therefore, this review covers the advances and challenges made in the chemical biofunctionalization of CP films for potential implantable devices. This is achieved by covalently attaching the biocompatible or biofunctional group to the CP backbone via a reactive functional group to create a material with physical and electronic properties that better matches biological tissue. A perspective is presented that this synthetic chemistry approach to biofunctionalization is valuable for the integration of CPs into commercial implantable bioelectronic devices.