▎ 摘　　要

We report on a photoelectrochemical immunoassay for the determination of microcystin-LR (MC-LR). It is based on the unique photoelectrochemical properties of a CdS-graphene composite that was deposited on fluorine-doped tin oxide glass prior to immobilization of the antibody (Ab) against MC-LR. The electrode was used for the label-free determination of MC-LR by monitoring the decrease in the photocurrent that result from the immunoreaction. The electrode displays a linear response to MC-LR in the range from 0.1 to 25 mu g L-1, a detection limit of 0.021 mu g L-1 (at S/N = 3), and can be applied to determine MC-LR in environmental water samples.