▎ 摘　　要

In this work, Mo-doped BiVO4 (Mo-BiVO4) and graphene nanocomposites were prepared and explored as photoactive material to construct a visible light-driven photoelectrochemical biosensor. The photoelectrochemical measurements indicated that suitable amount of graphene incorporated into Mo-BiVO4 greatly promoted the photocurrent response, owing to improved charge transfer rate and enhanced absorption of visible light. Moreover, graphene in the nanocomposites played a crucial role in immobilization of streptomycin aptamer through pi-pi stacking interaction. In the absence of streptomycin, photoelectrochemical aptasensor exhibited a weak photoresponse due to steric hindrance from the aptamer. After specific interaction between streptomycin and the aptamer, the sensor exhibited an enhanced photocurrent response to streptomycin, attributed to the oxidation of streptomycin molecules by photogenerated holes. Under optimal conditions, the designed photoelectrochemical sensor exhibited a linear photocurrent response to streptomycin in the concentration range of 0.1-100 nM, with a detection limit (3S/N) of 0.0481 nM. The applicability of the PEC aptasensor was successfully assessed by measuring streptomycin in commercial veterinary drugs. (C) 2017 Elsevier Ltd. All rights reserved.