Operando Microscopy of Photosynthetic Microbial Biohybrids Using Fluorescent Chemical Probes

Photosynthetic biohybrids, often in the form of biophotoelectrochemical devices, aim to achieve solar-to-chemical conversion by pairing biotic and abiotic materials to leverage the beneficial attributes of both. Numerous works have highlighted the importance of a well-tuned bio-electrode interface for high biophotoelectrode performance. However, the dynamics of these interfaces in photosynthetic biohybrids are poorly understood, necessitating the development of new tools to disentangle the various (bio)chemical processes occurring simultaneously. In this work, we construct an operando confocal microscopy platform to deeply analyze the dynamics in biofilm morphology, interfacial pH, and membrane potential. These methods assert that light availability is the main driver of microenvironment formation at the interface of a model Synechocystis-indium tin oxide bioelectrode. The potential of the electrode only induces a substantial impact outside of the potential range −0.32 to +0.48 V vs. Ag/AgCl at typical current densities. This toolkit provides a foundation for further elucidating interfacial dynamics and rational design of these systems and can be expanded to other bioelectrochemical constructs.