A signal polarity conversion photoelectrochemical immunosensor for neuron-specific enolase detection based on MgIn 2 S 4 -sensitized CsPbBr 3

A photoelectrochemical (PEC) immunosensor was designed based on MgIn 2 S 4 -decorated inorganic halide perovskite CsPbBr 3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr 3 was applied as the basic photoactive material owing to its excellent optical and electronic properties, which provide a good PEC performance for sensor construction. In order to improve the stability of this perovskite, the three-dimensional flower-like MgIn 2 S 4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn 2 S 4 provides large surface-active sites for CsPbBr 3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS 2 was used as a signal probe which fixed on detection antibody (Ab 2 ). When the target NSE was present, the photogenerated electrons produced by CuInS 2 were transferred to the test solution, and the polarity of PEC signal changes. Based on the above photosensitive materials and signal conversion strategy, the proposed PEC immunosensor showed favorable detection performance, and the linear detection range is 0.0001 ~ 100 ng/mL with a 38 fg/mL of detection limit. The proposed strategy improved the adhibition of CsPbBr 3 in the analytical chemistry field as well as provided a reference method for other protein detections. Graphical Abstract