Integrating Multifunctional Cu ₂ O@Cu‐MOF(4,4‐bpy)@Ag ₂ S With Molecularly Imprinted Polymers for Colorimetric‐Photoelectric Dual‐Mode Sensing

ABSTRACT Integrating photoelectrochemical (PEC) and colorimetric (CL) detection into a single platform enables cross‐validation, improved reliability, and high sensitivity, which critically relies on high‐performance muti‐functional signal tags. Herein, a rationally designed ternary Cu ₂ O@Cu‐MOF(4,4‐bpy)@Ag ₂ S heterostructure was synthesized via an in situ formation strategy with Ag ₂ S as a sensitizer. This composite serves as an efficient bifunctional signal probe, exhibiting a stable photocurrent and peroxidase‐mimicking activity. Ag ₂ S enhances charge separation for PEC response and offers Ag‐S anchoring sites for aptamer immobilization. The aptamer confers excellent specificity for bisphenol A (BPA) targets via selective molecular recognition. For sensor fabrication, a molecularly imprinted polymer (MIP) layer was prepared on an ITO electrode, creating target‐specific cavities after template removal. Upon capturing BPA within the MIP cavities, the target is selectively bound by the aptamer, precisely immobilizing the signal probe onto the electrode. This generates dual signals proportional to BPA concentration: a photocurrent and a colorimetric signal from TMB oxidation. The sensor achieves ultrasensitive detection, with PEC and CL linear ranges of 1.0 × 10 ^{− 1 3} –1.0 × 10 ^{− 6} m and 10.0–600.0 n m , and detection limits of 6.43 × 10 ^{− 14} m and 5.91 n m , respectively. The developed platform offers a promising approach for high‐performance dual‐mode sensing in environmental and food analysis.