Development of a novel biosensor based on a conducting polymer.

Abstract A new type of amperometric cholesterol biosensor was fabricated to improve the biosensor characteristics such as sensitivity and reliability. For this purpose, a novel immobilization matrix 2-(4-fluorophenyl)-4,7-di(thiophene-2-yl)-1 H -benzo[ d ]imidazole (BIPF) was electrochemically deposited on a graphite electrode and used as a matrix for the immobilization of cholesterol oxidase (ChOx). Due to strong π–π stacking of aromatic groups in the structures of polymer backbone and enzyme molecule, one can easily achieve a sensitive and reliable biosensor without using any membrane or covalent bond formation between the enzyme molecules and polymer surface. Moreover, through pendant fluorine group of the polymer, H-bond formation between with enzyme molecules and polymer was generated. Cholesterol was used as the substrate and amperometric response was measured in correlation with cholesterol amount, at −0.7 V vs. Ag/AgCl in phosphate buffer (pH 7.0). Consequently, optimum conditions for this constructed biosensor were determined. K M app, I max , LOD and sensitivity values were investigated and calculated as 4.0 nM, 2.27 µA, 0.404 µM and 1.47 mA/mM cm 2 , respectively. A novel and accurate cholesterol biosensor was developed for the determination of total cholesterol in food samples.