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.