Difunctional molecularly imprinted polymers and heterostructured CdS nanoparticle-sensitized ZnO nanorod arrays for antibody-free photoelectrochemical alpha-fetoprotein sensor

An antibody-free molecularly imprinted photoelectrochemical sensor was developed for alpha-fetoprotein (AFP) detection by means of difunctional polydopamine-based molecular imprinting polymers (PDA-MIP) on CdS nanoparticle-decorated ZnO nanorod arrays (CdS@ZnO NAs). Among them, the heterostructured CdS@ZnO NAs could accelerate the spatial separation of electron-hole pairs; while PDA-MIP not only provided abundant target recognition sites without expensive antibody, but also further increase the systemic photocurrent due to the enhanced light absorption capacity. After removing template molecules from PDA-MIP, the resulting imprinted cavities could be occupied by target AFP, leading to a decreased photocurrent. Moreover, the prepared sensor had a wide linearity in the range from 1 pg mL−1 to 1000 ng mL−1 with a low detection limit of 0.38 pg mL−1, as well as excellent selectivity and good stability. The application of AFP analysis in real human serum was also achieved, and the recoveries ranged from 99.2% to 105.2%.