Fabrication of graphene quantum dots/silicon nanowires nanohybrids for photoelectrochemical detection of microcystin-LR

A photoelectrochemical immunosensor was developed by incorporating graphene quantum dots (GQDs) and highly oriented silicon nanowires (SiNWs) for the determination of microcystin-LR (MC-LR) in water samples. The GQDs/SiNWs heterostructure was employed for signal transduction and biocompatible nanoscaffold for antibody (Ab) immobilization. The results showed that the fabricated GQDs/SiNWs electrode exhibited better photoelectrochemical performance than that of SiNWs. The specific recognition of MC-LR affected the optoelectronic properties of the Ab/GQDs/SiNWs electrode, leading to the photocurrent decreases. In the linear range from 0.1 μg L−1 to 10 μg L−1, the photocurrent decrease was proportional to the concentration of microcystin-LR and the linear regression equation was Y = 59.67 − 6.08X with a limit of detection of 0.055 μg L−1. The immunosensor possessed good sensitivity, selectivity and acceptable reusability for the determination of microcystin-LR, which was successfully applied in determining MC-LR in real water samples.