A Molecularly Imprinted Fluorescence Sensor Based on the ZnO Quantum Dot Core–Shell Structure for High Selectivity and Photolysis Function of Methylene Blue

ZnO quantum dots and CuFe2O4 nanoparticles were synthesized by chemical precipitation. The ZCF composite was created by the solvothermal method. A new molecularly imprinted fluorescence sensor (ZCF@MB-MIP) with unique optical properties and specific MB recognition was successfully generated. ZCF@MB-MIPs were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction and were applied for the selective detection of methylene blue (MB). The optimal working time of ZCF@MB-MIPs was 15 min, and the optimal working concentration was 37 mg·L–1. The fluorescence intensity was linearly quenched within the 0–100 μmol·L–1 MB range, and the detection limit was 1.27 μmol·L–1. The imprinting factor of the sensor (IF, K MB‑MIPs/N‑MIPs) was 5.30. At the same time, a real-time monitoring system was established for the photodegradation process of MB, which had the effect of reflecting the degradation degree of MB at any given time. Hence, ZCF@MB-MIPs are a promising candidate for use in MB monitoring, and they also provides a new strategy for constructing a multifunctional fluorescence sensor with a high selectivity and photolysis function.