A flexible visual detection of calcium peroxide in flour employing enhanced catalytic activity of heterogeneous catalysts binary copper trapped silica-layered magnetite nanozyme

Abstract

Herein, a novel heterogeneous nanozyme with peroxidase (POD)-like activity was conducted to achieve ultrasensitive visual detection of calcium peroxide (CaO2) in flour by the assembly of binary copper-trapped mesoporous silica layer coated magnetite nanoparticles (Fe3O4 @SiO2 @CuO NPs). The prepared nanozymes were characterized using HRTEM, SEM, FT-IR, XRD, DLS, and EIS, which displayed a dispersed core-shell structure with a uniform diameter of approximately 100 nm. The nanozymes exhibited remarkable and stable POD-like activity in a wide range of pH values, incubation temperature, and reaction time, and the optimum catalytic activity was obtained at pH 3.6, 37 °C, and 10 min. The quantification range of CaO2 of this method is 0.1–5 mM with a limit as low as 5.6 × 10−3 mM, and it is not affected by multiple interferences. In conclusion, this detection method is sensitive, stable, low-cost, and simple to operate, so it has broad application prospects in the detection of food additives such as CaO2.