The nanoelectrode-based electrochemical method has been widely used for single-cell analysis because of the advantages of high spatiotemporal resolution and in-situ detection capability.As an evolutional generation of the electrochemical analysis,photoelec-trochemical(PEC)sensors not only inherit the above-mentioned merits,but also possess a lower background and higher sensitivity,because they can operate under unbiased conditions.Moreover,electrodes are often impaired by nonspecific binding in complex bi-ological environments.Thus,an antifouling PEC ultramicrosensor is developed for unbiased single-cell analysis in this report.The ul-tramicrosensor is fabricated by self-assembling of photoactive material ZnCalnS nanosheets onto the carbon fiber ultramicroelec-trode surface and further dip-coating of a porous antifouling layer of cross-linked bovine serum albumin supported by carbon nano-tubes.Benefiting from the minimal influence of the ultrathin nanosheet on the ultramicroelectrode morphology and the smooth protective interface formed by the antifouling film,the obtained photoelectrode can be readily inserted into a single cell with negli-gible impact on cell viability and shows excellent antifouling performance.The PEC ultramicrosensor achieves selective detection of dopamine(DA)with a low detection limit(3.97 nmol/L)and exhibits good sensing capability for cytosolic DA in single PC12 cells.This exploration provides new opportunities for single-cell analysis.