A self-powered photocatalytic fuel sensor for single-cell analysis with high reliability

Electrochemical nanosensors possess high spatiotemporal resolution and easy quantification for single-cell analysis. However, the applied external potential may change the physiological state of cells and cause non-negligible secretion of molecules. Photoelectrochemical analysis not only inherits the merits of electrochemical methods but also with higher sensitivity and can operate without external potential. Nevertheless, the photoelectrode that is typically inserted into samples requires light excitation, leading to the introduction of another stimulus to the cells, which can cause cell membrane depolarization and thus affect cellular electrophysiological signals. We herein report a self-powered photocatalytic sensor based on a photoanode (outside the cell)-cell membrane-cathode (insert the cell) platform with a low detection limit (62 nM) for single-cell H 2 O 2 analysis. The photoanode located extracellularly avoids contact with many reductive small molecules in complex intracellular environments for ensuring highly selective detection of H 2 O 2 , and eliminates light stimulation effects on the inserted single cells. More importantly, the self-powered detection mode refrains from applying external potential, thus significantly reducing electrical stimulation to cells, showing high reliability in single-cell detection. This work provides a powerful tool for single-cell analysis.