Abstract: In this research, gold magnetic nanoparticles (Fe3O4@Au) were formed by self-assembling method. Its physical and chemical properties were characterized. A highly sensitive and selective enzyme-free enhanced electrochemical sensor based on the peroxidase-like activity of composite nanoparticles was prepared for the detection of ascorbic acid (AA). Electrochemical cyclic voltammetry (CV) was used to measure AA and the electrochemical detection system was optimized. The results showed that the established enzyme-free electrochemical sensor showed an extremely high sensitivity towards AA under the optimized conditions, with a good linear relationship between the current response (y) and the concentration of AA (x) in the range of 1–100 mmol/L, which was fitted with the equation: y = 867.81x + 3.860 8 (R2 = 0.991 9), and the detection limit was 0.011 7 mg/L. In addition, the electrochemical sensor was successfully applied in the detection of AA in real samples. In view of this, the proposed new enzyme-free electrochemical assay has great potential in the fields of food quality control and safety detection.

Key words: gold magnetic particles; enzyme-like activity; ascorbic acid; electrochemical detection; cyclic voltammetry