Polyaniline Langmuir−Blodgett Film Based Cholesterol Biosensor

Abstract

Cholesterol oxidase (ChOx) has been covalently linked to Langmuir−Blodgett (LB) monolayers of polyaniline\n(PANI)-stearic acid (SA) prepared onto indium−tin-oxide (ITO) coated glass plates via glutaraldehyde (Glu) chemistry.\nThese ChOx/Glu/PANI-SA LB film/ITO electrodes have been characterized by FT-IR, cyclic voltammetry, and\nscanning electron microscopy, respectively. The results of response measurements carried out on these bioelectrodes\nusing linear sweep voltammetry (LSV) reveal linearity from 25 to 400 mg/dL of cholesterol concentration with\nsensitivity of 88.9 nA mg^-1 dL. The linear regression analysis of bioelectrode reveals standard deviation and correlation\ncoefficient of 0.737 μA and 0.9988, respectively. The low value of the Michaelis−Menten constant of these bioelectrodes\nobtained as 1.21 mM for the immobilized enzyme indicates increased interaction between ChOx and cholesterol in\nthe PANI-SA LB film.