Measurement of total cholesterol using an enzyme sensor based on a printed hydrogen peroxide electrocatalyst

Abstract

Cholesterol is a major modifiable risk factor in cardiovascular disease and can be effectively managed by a combination of medication and monitoring. There continues to be a need for new point-of-care diagnostics to measure lipid panels, including total cholesterol. Enzyme assays based on the generation of hydrogen peroxide have been very effective in this regard. This work demonstrates the application of printed electrochemical sensors to the measurement of total cholesterol in serum. The assay uses the surfactant Triton X-100 to provide electrocatalytic enhancement of a silver paste screen-printed electrode to hydrogen peroxide, while also achieving effective solubilisation of total cholesterol from lipoprotein. The resulting biosensors employed 0.5% (v/v) Triton X-100 in PBS with 156 U mL⁻¹ cholesterol esterase and 60 U mL⁻¹ cholesterol oxidase. Measurement of total cholesterol in serum in the range of 0 to 10 mM had a sensitivity of 2.24 × 10⁻⁸ A mM⁻¹, with coefficient of determination of 0.984, detection limit of at least 2 mM and average relative standard deviation of 10.8% (n = 3).