Cholesterol Self-Powered Biosensor

Abstract

Monitoring the cholesterol level\nis of great importance, especially\nfor people with high risk of developing heart disease. Here we report\non reagentless cholesterol detection in human plasma with a novel\nsingle-enzyme, membrane-free, self-powered biosensor, in which both\ncathodic and anodic bioelectrocatalytic reactions are powered by the\nsame substrate. Cholesterol oxidase was immobilized in a sol–gel\nmatrix on both the cathode and the anode. Hydrogen peroxide, a product\nof the enzymatic conversion of cholesterol, was electrocatalytically\nreduced, by the use of Prussian blue, at the cathode. In parallel,\ncholesterol oxidation catalyzed by mediated cholesterol oxidase occurred\nat the anode. The analytical performance was assessed for both electrode\nsystems separately. The combination of the two electrodes, formed\non high surface-area carbon cloth electrodes, resulted in a self-powered\nbiosensor with enhanced sensitivity (26.0 mA M^–1 cm^–2), compared to either of the two individual\nelectrodes, and a dynamic range up to 4.1 mM cholesterol. Reagentless\ncholesterol detection with both electrochemical systems and with the\nself-powered biosensor was performed and the results were compared\nwith the standard method of colorimetric cholesterol quantification.