Peroxidase activity based on Cu2SnS3 quantum dots for the degradation and visual detection of zearalenone

For the first time, sulfur tin copper (Cu2SnS3) quantum dots with blue, green, yellow and red fluorescence were synthesized. It was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier infrared spectroscopy (FTIR). It was found that Cu2SnS3 quantum dots had excellent peroxidase catalytic properties and could effectively catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 to produce a dark blue product first and then a yellow product. Mie's constant shows that there is a greater binding capacity for substrates than natural horseradish peroxidase (HRP). FTIR shows that the catalytic activity of peroxide-mimetic enzymes of different colors of Cu2SnS3 quantum dots is related to the content of carboxyl groups (-COOH) on the surface of quantum dots. The essence of the catalytic activity originates from the generation of highly reactive hydroxyl radicals (•OH). Excitingly, Cu2SnS3 quantum dots were also able to degrade zearalenone (ZEN). Based on the peroxide-mimetic enzymatic activity and the catalytic degradation of Cu2SnS3 quantum dots for ZEN combined with molecularly imprinted polymers, a method was constructed for the degradation and visual detection of ZEN. Finally, the linear range for the determination of ZEN was 0.10–3.04 μmol/L with the limit of detection of 0.029 μmol/L. The color in the visual detection changes from yellow first to green and finally to dark blue. This method had been successfully used for the detection of ZEN in beer, corn and juice, respectively, with satisfactory results.