Trinuclear copper cluster-based COF with a high content of Cu–N2 single-atom sites: A multivariate signal-amplified photoelectrochemical aptasensor for the sensitive detection of mycotoxins

A novel amplified photoelectrochemical (PEC) aptasensor was developed based on the photoelectronic active and donor–acceptor (D–A) conjugated covalent organic framework (COF) for the efficient detection of zearalenone (ZEN). The D–A-conjugated COF synthesized through the reaction between trinuclear copper cluster (Cu3L3) and 4,4′,4′’-(1,3,5-triazine-2,4,6-triyl)trianiline (TAPT) (denoted as Cu3L3–TAPT–COF) comprised rich Cu–N2 single-atom sites and exhibited high photoactivity, narrow bandgap, and n-type semiconductor feature. It was simultaneously employed as PEC electrode and bioplatform for anchoring single-stranded DNA. Moreover, the p-type ZnIn2S4 semiconductor anchors hairpin probe strands that hybridized with the ZEN-target aptamer. By combining the target-modulated competitive binding method and the multivariate signal-amplified strategy, the Cu3L3–TAPT–COF-based PEC aptasensor exhibited a wide linear range from 0.1 pg mL−1 to 20 ng mL−1 and a low detection limit of 24 fg mL−1, along with excellent and widespread practical applicability, offering promising applications in food safety.