Label-free photoelectrochemical biosensor for alpha-fetoprotein detection based on Au/CsxWO3 heterogeneous films

In this work, a novel label-free photoelectrochemical (PEC) biosensor based on Au/CsxWO3 heterogeneous films with low background noise and excellent sensitive detection of alpha-fetoprotein (AFP) was proposed. We prepared Au/CsxWO3 heterogeneous films by different methods including template removal and spin coating. The surface plasmon resonances (SPR) of Au film and CsxWO3 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.