Tetraethylorthosilicate film modified with protein to fabricate cholesterol biosensor

Sol–gel derived tetraethylorthosilicate (TEOS) films were prepared by spin coating method on indium tin oxide (ITO) coated glass plate. Hydrophobic interaction method was used to coat the bovine serum albumin film over the surface of tetraethylorthosilicate sol–gel film to minimize cracking, biofouling and to improve the stability of the film. Cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) were immobilized using covalent linkage with bovine albumin serum film to enhance the loading of the enzyme to improve the sensitivity of biosensor. Further ITO–TEOS–BSA–ChOx/HRP film was characterized by UV–vis, FTIR and SEM techniques. The optical response of the ITO–TEOS–BSA–ChOx/HRP biosensor was found to be linear in the range of 2–8 mM for cholesterol concentration with response time approximately 20 s. Amperometric response of ITO–TEOS–BSA–ChOx/HRP was observed to be linear in the range of 2–12 mM of cholesterol concentration with 10-s response time. Michaelis–Menten constant was calculated 21.2 mM .The shelf life of ITO–TEOS–BSA–ChOx/HRP biosensor was approximately about 8 weeks in desiccated conditions at room temperature.