Polydopamine-coated photoautotrophic bacteria for improving extracellular electron transfer in living photovoltaics

Living photovoltaics are microbial electrochemical devices that use whole cell–electrode interactions to convert solar energy to electricity. The bottleneck in these technologies is the limited electron transfer between the microbe and the electrode surface. This study focuses on enhancing this transfer by engineering a polydopamine (PDA) coating on the outer membrane of the photosynthetic microbe Synechocystis sp. PCC6803. This coating provides a conductive nanoparticle shell to increase electrode adhesion and improve microbial charge extraction. A combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis absorption, and Raman spectroscopy measurements were used to characterize the nanoparticle shell under various synthesis conditions. The cell viability and activity were further assessed through oxygen evolution, growth curve, and confocal fluorescence