Ultrasensitive cholesterol biosensor based on enzymatic silver deposition on gold nanoparticles modified screen-printed carbon electrode

- A biosensor based on enzymatic Ag deposition on Au NPs/SPE was developed.
- The cholesterol biosensor was characterized by SEM, XPS and CV.
- The current of Ag depended linearly on the concentration of cholesterol.
- The biosensor showed outstanding specificity and acceptable reproducibility.

Cholesterol is one of the essential structural constituents of cell membranes. Determination of cholesterol is of great importance in clinical analysis because the level of cholesterol in serum is an indicator in the diagnosis and prevention of heart diseases. In this work, a simple and ultrasensitive cholesterol biosensor based on enzymatic silver deposition was designed by immobilizing cholesterol oxidase (CHOD) and cholesterol esterase (CHER) onto the surface of gold nanoparticles (Au NPs) modified screen-printed carbon electrode (SPE). By the catalytic action of CHER and CHOD, the cholesterol was hydrolyzed to generate hydrogen peroxide (H2O2) which can reduced the silver (Ag) ions in the solution for the deposition of metallic Ag on the surface of Au NPs modified SPE. The ultrasensitive detection of cholesterol was achieved by anodic stripping voltammetry (ASV) measurement of the enzymatically deposited Ag. The influence of relevant experimental variables was optimized. The anodic stripping peak current of Ag depended linearly on the concentration of cholesterol in the range of 5-5000 μg/mL with the regression correlation coefficient of 0.9983. A detection limit of 3.0 μg/mL was attained by 3 sigma-rule. In addition, the ultrasensitive cholesterol biosensor exhibited higher specificity, acceptable reproducibility and excellent recoveries for cholesterol detection.

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