Biological Transformation of AgI on MOF-on-MOF-Derived Heterostructures: Toward Polarity-Switchable Photoelectrochemical Biosensors for Neuron-Specific Enolase

The sensitive detection of neuron-specific enolase (NSE)as a biomarkerfor lung cancer at an early stage is critical but has long been achallenge. The emergence of polarity-switchable photoelectrochemical(PEC) bioanalysis has opened up new avenues for developing highlysensitive NSE sensors. In this study, we present such a biosensordepending on the bioinduced AgI transition on MOF-on-MOF-derived semiconductorheterojunctions. Specifically, treatment of ZnO@In2O3@AgI by bioproduced H2S can in situ generate theZnO@In2O3@In2S3@Ag2S heterojunction, with the photocurrent switching from thecathodic to anodic one due to the changes in the carrier transferpathway. Linking an NSE-targeted sandwich immunorecognition with labeledalkaline phosphatase (ALP) catalyzed generation of H2S,such a phenomenon was correlated to NSE concentration with good performancein terms of selectivity and sensitivity and a low detection limitof 0.58 pg/mL. This study offered a new perspective on the use ofMOF-on-MOF-derived heterostructures for advanced polarity-switchablePEC bioanalysis.