Polypyrrole as Electrically Conductive Biomaterials: Synthesis, Biofunctionalization, Potential Applications and Challenges

Electrical phenomenon is ubiquitous in any biological system. However, most synthetic biomaterials are insulators to either electrical or ionic current. To mimic the electrical and ionic conductivities of natural tissues, electrically conductive polymers have been studied and are becoming a new class of biomaterials. This chapter focuses on polypyrrole, one of the most widely investigated synthetic and intrinsically conductive polymers. Polypyrrole is a heterocyclic polymer that is both electrically conductive and ionically active. It can be easily synthesized through electrochemical polymerization or oxidative polymerization. Because of its unique properties, polypyrrole has been studied for sensing, drug delivery, and actuation. Because of its good biocompatibility, it has been used to interface electrical elements and tissues, either for recording or stimulation purpose. Polypyrrole can also be chemically modified to carry functional groups and biomolecules, allowing both specific biological recognition and electrical stimulation. This chapter also discusses a unique soft polypyrrole membrane that can be easily used as biomaterials. Hopefully, the readers of this chapter would appreciate the importance of electrical conductivity for biomaterials and the usefulness of polypyrrole.