Colorimetric detection of cholesterol based on peroxidase mimetic activity of GoldMag nanocomposites

Herein, Gold and magnetic particles (GoldMag), an enzyme mimetic of horseradish peroxidase (HRP), have been designed to construct a colorimetric sensor for cholesterol (Cho). The well-dispersed GoldMag was successfully prepared by green reduction using a self-assembly method based on the surface amino groups, and characterized by Fourier transform infrared (FTIR), X-Ray Photoelectron Spectroscopic (XPS) techniques. In the presence of H₂O₂, the resulting nanocomposites possessed enhanced intrinsic peroxidase-like activity and could catalytically oxidize 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) to produce a green colored product, which could be observed apparently by the naked eye. Based on the outstanding catalytic activity, the designed colorimetric sensor displayed a linear response for cholesterol in the range from 0.1 mg/mL to 7.5 mg/mL with a detection limit as low as 0.003 mg/mL. The proposed method was validated to determine cholesterol in real samples with satisfactory results.