An ultrasensitive photoelectrochemical sensing platform: Integrating molecularly imprinted polymers with a MOF-on-MOF heterostructure for detecting trace oxytetracycline in food and water environment

To tackle the issue of interference from structural analogs in oxytetracycline (OTC) detection and to meet the growing demand for food safety monitoring, a photoelectrochemical (PEC) sensor employing molecular imprinting on a MOF-on-MOF heterojunction as photoactive substrate was constructed to achieve selective and accurate determination of OTC. The solvothermal and stirring synthesis of the MIL-125-NH 2 @Cu-hemin MOF heterojunction exhibit enhanced photocurrent, owing to efficient charge separation and expanded light absorption. The molecularly imprinted polymer (MIP) featured specific cavities to selectively capture OTC and regulate interfacial electron transfer. Under optimal conditions, the sensor showed a wide linear range (0.1 nmol L −1 –10 mmol L −1 ), a low detection of limit (LOD) of 42 pmol L −1 , and a limit of quantification (LOQ) of 140 pmol L −1 . By combining heterojunction-optimized photoelectric properties with MIP-based selective recognition, the sensor successfully detected OTC in complex food matrices, demonstrating its potential for food safety.