A ZnIn2S4/Ag2CO3 Z-scheme heterostructure-based photoelectrochemical biosensor for neuron-specific enolase

An efficient photo-to-electrical signal is pivotal to photoelectrochemical (PEC) biosensors. In our work, a novel PEC biosensor was fabricated for the detection of neuron-specific enolase (NSE) based on a ZnIn 2 S 4 /Ag 2 CO 3 Z-scheme heterostructure. Due to the overlapping band potentials of the ZnIn 2 S 4 and Ag 2 CO 3 , the formed Z-scheme heterostructure can promote the charge separation and photoelectric conversion efficiency. And the concomitant Ag nanoparticles in Ag 2 CO 3 provided multiple functions to enhance the PEC response of the Z-scheme heterostructure. It acts not only as a bridge for the transfer of carriers between ZnIn 2 S 4 and Ag 2 CO 3 , promoting the constructed Z-scheme heterostructure, but also as electron mediators to accelerate the transfer of photogenerated carriers and improve the capture of visible light of the Z-scheme heterostructure by surface plasmon resonance (SPR). Compared with single Ag 2 CO 3 and ZnIn 2 S 4 , the photocurrent of the designed Z-scheme heterostructure increased more than 20 and 60 times respectively. The fabricated PEC biosensor based on a ZnIn 2 S 4 /Ag 2 CO 3 Z-scheme heterostructure exhibits sensitive detection to NSE, and presents a linear range of 50 fg·mL −1  ~ 200 ng·mL −1 with a limit of detection of 4.86 fg·mL −1 . The proposed PEC biosensor provides a potential approach for clinical diagnosis.