A Cholesterol Biosensor Based on Entrapment of Cholesterol Oxidase in a Silicic Sol‐Gel Matrix at a Prussian Blue Modified Electrode

Abstract A cholesterol biosensors fabricated by immobilization of cholesterol oxidase (ChOx) in a layer of silicic sol‐gel matrix on the top of a Prussian Blue‐modified glassy carbon electrode was prepared. It is based on the detection of hydrogen peroxide produced by ChOx at −0.05 V. The half‐lifetime of the biosensor is about 35 days. Cholesterol can be determined in the concentration range of 1×10 −6 −8×10 −5 mol/L with a detection limit of 1.2×10 −7 mol/L. Normal interfering compounds, such as ascorbic acid and uric acid do not affect the determination. The high sensitivity and outstanding selectivity are attributed to the Prussian Blue film modified on the sensor.