A molecularly imprinted electrochemiluminescence sensor based on mimic enzyme ZIF-90 and MnO2/g-C3N4 magnetic particles for detection of methidathion

Methidathion (MTDT), a common organophosphorus pesticide with high insecticidal activity, is widely used for pest control. However, the misuse of MTDT leads to widespread residues and endangers human health. Therefore, it is crucial to develop a simple and highly sensitive method for the detection of MTDT residues. Herein, ZIF-90/MnO 2 /g-C 3 N 4 /Fe 3 O 4 composite particles were synthesized: The  MnO 2 nanosheets could absorb the energy of the excited g-C 3 N 4 to quench the ECL of g-C 3 N 4 while ZIF-90 acted as a mimetic enzyme to catalyze the formation of thiocholine from MTDT. The thiocholine caused the reduction of MnO 2 to Mn 2+ , restoring the ECL signal of g-C 3 N 4 . Combined with molecular imprinting technique, an electrochemiluminescence sensor was constructed for the determination of MTDT. The determination range was 1.00 × 10 –9  ~ 7.00 × 10 –7  g/L, and the detection limit was 6.58 × 10 –10  g/L. Structurally similar organophosphorus pesticides showed no cross-reactivity. The method has high sensitivity and specificity, and has been successfully applied to the determination of MTDT residue in fruits with recoveries in the range 93.75% ~ 102.37%. Graphical abstract