Photoelectrochemical immunosensor for the sensitive detection of neuron-specific enolase based on the effect of Z-scheme WO3/NiCo2O4 nanoarrays p-n heterojunction

In this study, a signal-on type PEC immunosensor was constructed to detect neuron-specific enolase (NSE) via Z-scheme WO3/NiCo2O4 p-n heterojunction with cactus-like structure used as photoactive materials and MnxCd1-xS superset of Au NPs (MCS superset of Au NPs) as signal labels. Firstly, Z-scheme WO3/NiCo2O4 heterojunction could accelerate the separation efficiency of carriers and well-matched photoactive materials may promote charge migration, which resulted in WO3/NiCo2O4 generating strong and stable current. In addition, Z-scheme WO3/NiCo2O4 heterojunction directly grown on the surface of FTO via hydrothermal method facilitated the preparation of PEC immunosensor with outstanding stability. Secondly, an efficient signal amplification strategy was proposed by MnxCd1-xS superset of Au NPs incubating with signal antibody (Ab(2)). On the one hand, the well-matched energy levels of MnxCd1-xS with WO3/NiCo2O4 boosted the photo-generated electrons transferred to the electrode; on the other hand, the LSPR effect of Au may convert thermion to photocurrent to achieve signal amplification. Based on the above strategies, a PEC immunosensor with outstanding reproducibility and stability was obtained for sensitive detection of NSE. Under the optimum experimental conditions, current response range of the constructed signal amplification PEC sensor to NSE was 0.1 pg/mL similar to 50 ng/mL and the detection limit was 0.07 pg/mL (S/N = 3). After the application tests in the detection of actual samples, the feasibility of the prepared PEC immunosensor with excellent selectivity, high sensitivity and satisfactory reproducibility was verified and the satisfactory results were obtained.

Automated summary

In this study, a signal-on type PEC immunosensor was constructed to detect neuron-specific enolase (NSE) using Z-scheme WO3/NiCo2O4 p-n heterojunction and MnxCd1-xS superset of Au NPs. The immunosensor showed outstanding stability and reproducibility, as well as excellent selectivity and high sensitivity.