Photoelectrochemical immunosensing of prostate-specific antigen (PSA) based on co-electrodeposited polyaniline-graphene quantum dot-tungsten oxide nanocomposite decorated with gold nanoparticles.

Sensitive and accurate prostate-specific antigen (PSA) detection plays an important role in the early diagnosis of prostate cancer, but achieving such detection remains challenging due to the extremely low concentration of PSA biomarkers in human serum. In this work, a novel photoelectrochemical (PEC) immunosensor for ultra-trace value detection of PSA was prepared based on a synergistic nanocomposite composed of polyaniline, graphene quantum dots, tungsten oxide, and gold (PANI-GQDs-WOx/Au). The PANI-GQDs-WOx nanocomposite was co-electrodeposited on the graphenized screen-printed carbon electrode (GSCPE), which was subsequently modified with gold nanoparticles. The rational design of engineered nanocomposites provided enhanced electrical conductivity, efficient electron transfer, enhanced photocurrent response, superior catalytic activity, and an ideal substrate for stable immobilization of the bioreceptor. Under the optimized conditions, the PEC immunosensor exhibited significantly improved photocatalytic performance, achieving a very low limit of detection of 75 fg mL-1 and a wide linear range from 0.1 pg mL-1 to 100 ng mL-1. Most importantly, the performance of the immunosensor was successfully confirmed in real human serum samples, without dilution and deproteinization. These results highlight the promising potential of PANI-GQDs-WOx/Au nanocomposite for the development of rapid and accurate point-of-care diagnostic platforms and are an important step towards improving prostate cancer diagnosis.