A photoelectrochemical immunosensor based on natural pigment sensitized ZnO for alpha-fetoprotein detection

In this work, ZnO flower-rod arrays (ZnO FRs) were prepared by chemical deposition method and sensitized with natural pigment. The main component of natural pigment was chlorophyll which was extracted from fresh Ficus lacor leaves with simple method. And then a photoelectrochemical (PEC) immunosensor was constructed based on the natural pigment sensitized ZnO FRs (NP-ZnO FRs) and used to detect alpha-fetoprotein (AFP). The results show that the absorbance spectrum of visible light is enhanced for NP-ZnO FRs compared with pure ZnO and the photocurrent is strengthened. The electron transfer is restricted at the interface of ZnO and AFP due to the insulativity of the protein, therefore, the photocurrent is changed. In the measurement range of 0.005–50 ng·mL −1 , the logarithm of the measured concentrations ( c ) has a good linear relationship with the output photocurrent of the immunosensor. The rapid and accurate detection of AFP by the developed PEC immunosensor is realized. Moreover, the PEC immunosensor has high stability and is used to test AFP in the serum of clinical patients. Compared with ELISA method, the result by the PEC immunosensor is reliable. It means that the proposed method has good applicability and this work pave a way to construct visible light PEC biosensor.