In Vivo Voltammetric Imaging of Metal Nanoparticle-Catalyzed Single-Cell Electron Transfer by Fermi Level-Responsive Graphene

Metal nanomaterials can facilitate microbial extracellular electron transfer(EET)in the electrochemically active biofilm.However,the role of nanomaterials/bacteria interaction in this process is still unclear.Here,we reported the single-cell voltammetric imaging of Shewanella oneidensis MR-1 at the single-cell level to elucidate the metal-enhanced EET mechanism in vivo by the Fermi level-responsive graphene electrode.Quantified oxidation currents of~20 fA were observed from single native cells and gold nanoparticle(AuNP)-coated cells in linear sweep voltammetry analysis.On the contrary,the oxidation potential was reduced by up to 100 mV after AuNP modification.It revealed the mechanism of AuNP-catalyzed direct EET decreasing the oxidation barrier between the outer membrane cytochromes and the electrode.Our method offered a promising strategy to understand the nanomaterials/bacteria interaction and guide the rational construction of EET-related microbial fuel cells.