Nanozyme-driven in-situ Z-scheme heterojunction based photoelectrochemical platform for picomolar detection of 17β-estradiol

The development of selective and sensitive sensing platforms is of significance for food safety, pathogen detection, and public health. Herein, we present a novel photoelectrochemical (PEC) sensing platform that integrates molecularly imprinted polymers (MIPs)-target-aptamer sandwich and a nanozyme-driven in-situ Z -scheme heterojunction to enhance selectivity and sensitivity. The MIPs on 96-well plates selectively capture targets 17β-estradiol (E2), one of the hormonally active compounds. The captured targets are then detected via a sandwich structure formed by E2-specific aptamer-conjugated CeO₂@UiO-66 nanozymes, which possess alkaline phosphatase (ALP) activity. The nanozymes catalyze the hydrolysis of sodium thiosulfate, generating H 2 S and triggering the in-situ vulcanization of Bi₂O₃ into Bi₂O₃@Bi₂S₃ Z -scheme heterojunctions. This heterojunction enhances charge separation under illumination, resulting in a target-proportional photocurrent. The resulting sensor exhibits excellent analytical performance for E2, with a low detection limit of 76.2 pM. This innovative strategy integrates MIPs with an aptamer-based sandwich architecture to enhance selectivity, while simultaneously exploiting nanozyme-driven in-situ heterojunction formation for signal amplification, thereby offering a highly efficient approach for sensitive and selective analysis.