Label-free photoelectrochemical biosensor for alpha-fetoprotein detection based on Au/Cs_xWO₃ heterogeneous films

In this work, a novel label-free photoelectrochemical (PEC) biosensor based on Au/Cs_xWO₃ heterogeneous films with low background noise and excellent sensitive detection of alpha-fetoprotein (AFP) was proposed. We prepared Au/Cs_xWO₃ heterogeneous films by different methods including template removal and spin coating. The surface plasmon resonances (SPR) of Au film and Cs_xWO₃ semiconductor nanocrystals largely improved the photoelectrochemical properties of the electrodes and enhanced the photocurrent. Under the optimal conditions, the prepared PEC biosensor showed a linear response between photocurrent variation and the logarithm of AFP concentration in the range from 0.01 ng/mL to 500 ng/mL with a low detection limit of 7 pg/mL. In addition, the proposed PEC biosensor had excellent specificity, repeatability, long-term stability and showed satisfactory results in the analysis of human serum samples, which would have great prospect in clinical application and biological analysis in the future.