Photoelectrochemical detection of alpha-fetoprotein based on ZnO inverse opals structure electrodes modified by Ag(2)S nanoparticles

In this work, a new photoelectrochemical biosensor based on Ag(2)S nanoparticles (NPs) modified macroporous ZnO inverse opals structure (IOs) was developed for sensitive and rapid detection of alpha fetal protein (AFP). Small size and uniformly dispersed Ag(2)S NPs were prepared using the Successive Ionic Layer Adsorption And Reaction (SILAR) method, which were adsorbed on ZnO IOs surface and frame work as matrix for immobilization of AFP. The composite structure of ZnO/Ag(2)S expanded the scope of light absorption to long wavelength, which can make full use of the light energy. Meanwhile, an effective matching of energy levels between the conduction bands of Ag(2)S and ZnO are beneficial to the photo-generated electrons transfer. The biosensors based on FTO (fluorine-doped tinoxide) ZnO/Ag(2)S electrode showed enough sensitivity and a wide linear range from 0.05 ng/mL to 200 ng/mL with a low detection limit of 8 pg/mL for the detection of AFP. It also exhibited high reproducibility, specificity and stability. The proposed method was potentially attractive for achieving excellent photoelectrochemical biosensor for detection of other proteins.