Photoelectrochemical apta-biosensor for zeatin detection based on graphene quantum dots improved photoactivity of graphite-like carbon nitride and streptavidin induced signal inhibition

•A sensitive aptamer-based photoelectrochemical biosensor was fabricated for zeatin detection.•Graphite-like carbon nitride was used as photoactivity material and graphene quantum dots as photoactivity enhancer.•The developed method showed wide linear range from 0.1 to 100nM and low detection limit of 0.031nM.•This method can be applied to detect zeatin in 10% plant tissue culture with recoveries from 94% to 105%.