Application of electrochemically prepared poly-N-methylpyrrole-p-toluene sulphonate films to cholesterol biosensor

Cholesterol oxidase (ChOx) has been immobilized onto electrochemically prepared poly-N-methylpyrrole P(NMPY)-p-toluene sulphonate (PTS)/indium–tin-oxide (ITO) films by physical adsorption and entrapment techniques, respectively. The ChOx(entrapped)-P(NMPY)-PTS/ITO, ChOx(physisorbed)-P(NMPY)-PTS/ITO along with ferrocene carboxylic acid (FeMC) mediated ChOx(physisorbed)-P(NMPY)-PTS/ITO films have been characterized using cyclic voltammetry (CV), Fourier-transform-infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques, respectively. Compared to ChOx(entrapped)-P(NMPY)-PTS/ITO (0.205 mA (mM cm2)−1) and ChOx(physisorbed)-P(NMPY)-PTS/ITO (0.24 mA (mM cm2)−1) electrodes, the ChOx(physisorbed)–FeMC(physisorbed)-P(NMPY)-PTS/ITO bio-electrode exhibits increased sensitivity (0.45 mA (mM cm2)−1) and decreased response to interferent (ascorbic acid, uric acid, urea, glucose). A tentative mechanism for the immobilization of cholesterol oxidase onto P(NMPY)-p-toluene sulphonate (PTS) films has been proposed.