ZIF-8-derived double-shelled hollow ZnS nanocages: a new signal transducer for photoelectrochemical immunoassay of neuron-specific antigen-based neuroblastoma biomarker.

Methods based on photoelectrochemical immunoassay have been utilized for the quantitative monitoring of neuron-specific antigen (NSE) with neuroblastoma patients, but most provide only low sensitivity. In this contribution, a simple and feasible photoelectrochemical immunoassay based on ZIF-8-derived double-shelled hollow ZnS nanocages (ZnS NCs) was applied to the split-type photocurrent measurement of NSE in biological fluids, accompanied by an enzyme-catalyzed system for synergistic amplification. Glucose oxidase (GOx)-labeled anti-NSE secondary antibody was utilized to form a sandwiched immunoreaction on capture antibody-coated microplate, whereas ZnS NCs with strong and stable photocurrents were employed to generate the detectable photocurrent. Subsequently, GOx catalyzed the glucose substrate to produce hydrogen peroxide, thereby causing the change in the photocurrent of double-shelled hollow ZnS nanocages. Followed by optimizing experimental conditions, the photoelectrochemical immunoassay displayed good photocurrent responses within the dynamic range 1.0-10000 pg mL-1 at a low detection limit of 0.59 pg mL-1 NSE. Good reproducibility and high specificity were acquired for determination of  NSE standards. Such a highly favourable analytical performance could be achieved even in human serum samples at different dilutions.