Protein and polysaccharide-composite sol–gel silicate film for an interference-free amperometric glucose biosensor

A novel permselective, organic–inorganic-hybrid, sol–gel silicate-film was chemically modified on an anodized platinum (Pt) electrode surface to form a selective, sensitive and interference-free amperometric glucose biosensor. This permselective hybrid sol–gel film consists of three organo-silanes [i.e., 3-aminopropyltriethoxysilane (APTES); tetraethoxysilane (TEOS); triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane (FAS)] and two biomacromolecules [i.e., bovine serum albumin (BSA) and a chitosan (CHIT)]. After the addition of the film to the Pt electrode, glucose oxidase (GOx) was covalently immobilized within the film with glutaraldehyde. The incorporation of the BSA and CHIT not only enhanced the permselectivity of H2O2 but also improved the activity of the immobilized GOx. The CHIT effectively suppressed any swelling of the film. Moreover, the conjugation of the FAS was especially effective in reducing the interference currents of AA and UA to levels less than 1/400 and 1/300 of the current of H2O2. The resulting organic–inorganic-hybrid sol–gel-film-based amperometric glucose biosensor exhibited rapid and sensitive responses to glucose (100% response in <3 s, sensitivity: 1.84 μA mM−1, detection limit: 0.032 mM), and the highly selective determination of glucose was possible, even in the presence of 0.1 mM AA and UA.