Enzyme free electrochemical cholesterol sensor based on carbon paste electrode modified with ionic liquid and molecularly imprinted polymer.

Blood cholesterol levels are an important factor in clinical studies. In this work, a sensitive and selective electrochemical sensor for cholesterol was developed using a carbon paste electrode (CPE) modified with an ionic liquid (IL) and a molecularly imprinted polymer (MIP). Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive Spectroscopy (EDS) confirmed the successful modification of the electrode surface with the imprinted polymer. The electrochemical behavior of the sensor was investigated via cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Optimal performance conditions were first determined for the incubation time, analyte extraction solvent, monomer-to-analyte ratio, and buffer pH. Good linear behavior was noted over the 5 to 50 nM cholesterol concentration range in buffer with a limit of detection (LOD) of 3.62 nM and the limit of quantitation (LOQ) value of 10.98 nM using potassium ferri/ferrocyanide as the external redox probe. To investigate the application of this sensor in real samples, four serum samples were selected and analyzed. The cholesterol concentrations obtained using the developed electrochemical sensor were in good agreement with those measured by the standard enzymatic-colorimetric technique.