Molecularly imprinted electrochemiluminescence sensor based on flake-like Au@Cu:ZIF-8 nanocomposites for ultrasensitive detection of malathion

The combination of electrochemiluminescence (ECL) and molecularly imprinted polymer (MIP) techniques offers distinct for detecting organophosphorus pesticides (OPs). Herein, a novel flake-like nanocomposites Au@Cu:ZIF-8 was successfully synthesized, as to design a molecularly imprinted electrochemiluminescence (MIP-ECL) sensor for the detection of malathion (MAL). The doped Cu2+ as a co-reaction promoter facilitated the generation of the active intermediate SO4•− for the cathodic reaction system with K2S2O8 as the co-reactant, while AuNPs were used as an excellent catalyst, further enhancing the ECL strength of the overall reaction system. Subsequently, MIP film was formed by the electropolymerization of Benzo[1,2-b:4,5-b′]dithiophene-4,8-dione as a functional monomer and MAL as a template molecule on the electrode surface. Confirmation of this process was achieved through molecular docking technique, which indicated that template molecule and functional monomer were tightly bound through non covalent bonds. The ECL signal was controlled by the elution and incubation of MAL by the MIP, thus establishing a novel method for MAL detection. The sensor showed a good linear relationship in the range of 10 pg/mL to 0.1 μg/mL with a detection limit of 0.18 pg/mL (S/N = 3). Furthermore, the recoveries of MAL detection in apple, cabbage and tomato samples ranged from 91.94% to 104.50%, indicating that the sensor offers potential applications for trace analysis of OPs in food and agricultural products.