A signal amplifying photoelectrochemical immunosensor based on the synergism of Au@CoFe2O4 and CdS/NiCo2O4 for the sensitive detection of neuron-specific enolases

Neuron-specific enolase (NSE), a marker of small cell lung cancer, is over-expressed in patient serum. To reduce the threat of lung cancer to human health and life, a rapid and effective method for the sensitive detection of NSE is necessary. In this study, a sandwich-type photoelectrochemical (PEC) immunosensor for the rapid and sensitive detection of NSE was constructed. To provide a powerful and stable photocurrent signal, the bandgap-matched CdS/NiCo2O4 was used as the substrate material. In addition, Au@CoFe2O4, which can form a step electron transfer mode with NiCo2O4, was proposed for the first time as a second antibody (Ab2) marker to amplify photoelectric signals. The constructed signal-amplified PEC immunosensor showed good linearity in the range of 1 pg/mL − 100 ng/mL with a detection limit as low as 0.24 pg/mL (S/N=3). The constructed PEC immunosensor has shown excellent stability, selectivity, reproducibility, and repeatability. It showed recoveries in the range of 98% − 105% and relative standard deviations (RSD) within 5% in sample analysis. The method proposed in this study is expected to be more widely used in the future for the detection of other disease markers as well as environmental pollutants.