Cholesterol biosensor based on electrophoretically deposited conducting polymer film derived from nano-structured polyaniline colloidal suspension

Cholesterol oxidase (ChOx) has been covalently immobilized onto electrophoretically deposited conducting polymer film (on indium-tin-oxide (ITO) glass plate) derived from nano-structured polyaniline (PANI) colloidal suspension using N-ethyl-N′-(3-dimethylaminopropyl) corbodiimide (EDC) and N-hydroxysuccinimide (NHS) chemistry. These PANI/ITO and ChOx/PANI/ITO electrodes have been characterized using ultraviolet-visible (UV-vis), Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM), and impedance spectroscopy techniques, respectively. These ChOx/PANI/ITO bio-electrodes exhibit linearity from 25 to 400 mg dL−1 of cholesterol, detection limit as 25 mg dL−1 and sensitivity as 7.76 × 10−5 Abs (mg/dL)−1. The value of the apparent Michaelis–Menten constant (Kmapp) calculated from amperometric response studies has been found to be 0.62 mM for ChOx/PANI/ITO bio-electrode.