A sandwich-type photoelectrochemical sensor constructed with a signal amplification strategy based on the upconversion luminescence characteristics of Ag@NCQDs for sensitive detection of neuron specific enolase.

In this paper, BiS/AgBiS composite nanomaterials and PDA@Ag@N-CQDs were synthesized, and used as substrates and second antibody label respectively to construct a sandwich photoelectrochemical (PEC) sensor. The upconversion luminescence effect of N-CQDs can convert long wavelength light into short wavelength light that can be utilized by the substrate material, which can provide additional excitation light energy for the substrate material and further enhance the photoelectric response. Besides, Ag has SPR effect and can also promote electron transfer. The proposed sandwich immunosensor achieves detection of NSE in the concentration range of 0.001 ng mL to 100 ng mL, with a detection limit of 0.28 pg mL (S/N = 3). What's more, the proposed sensor also exhibits good stability, selectivity, as well as reproducibility, indicating its promising application prospects.