Development of electrically-conducting biohybrid materials based on electroactive bacteria and conjugated polymers: Review and perspectives

The application of conjugated polymers (CPs) in charge storage devices, biosensors, and microbial fuel cells increased their importance in the field of electronics. To reveal their full potential, CPs can be modified with the use of various doping ions, ionic liquids, as well as nano and biomaterials. Recently, immobilization of electroactive bacteria within CPs has emerged as a new route towards extending the applicability of CPs. The presence of extracellular polymeric substances, opposite charged components of a bacterial cell wall, c-cyto-chromes, pili, and electron shuttles has been shown to mediate the extracellular electron transfer making CPs-bacteria biohybrids effective in electrical conductivity and charge storage. The key role in the development of electrically-conducting biohybrid materials is played by the process of bacteria immobilization, which should allow for an effective electron transfer between CPs and electroactive bacteria. Consequently, the surface of CPs and electroactive bacteria should be compatible with each other in terms of surface wettability, roughness, charge carriers, and delocalization of electrons. The aim of this review is to summarize recent attempts in the effective immobilization of the whole bacterial cells and their proteins on the surface or within CPs, particularly poly(3,4-ethylenedioxythiophene) and polypyrrole, to design novel type of electrically-conducting biohybrid materials with the potential applicability in organic electronics and bioelectronics.