title: Covalent immobilization of glucose oxidase on well-defined poly(glycidyl methacrylate)-Si(111) hybrids from surface-initiated atom-transfer radical polymerization.
abstract: A simple one-step procedure was employed for the covalent immobilization of an atom-transfer radical polymerization (ATRP) initiator, via the robust Si-C bond, on the hydrogen-terminated Si(111) surface (Si-H surface). Well-defined poly(glycidyl methacrylate) [P(GMA)] brushes, tethered directly on the (111)-oriented single-crystal silicon surface, were prepared via surface-initiated ATRP. Kinetics study on the surface-initiated ATRP of glycidyl methacrylate revealed that the chain growth from the silicon surface was consistent with a "controlled" process. A relatively high concentration of glucose oxidase (GOD; above 0.2 mg/cm2) could be coupled directly to the well-defined P(GMA) brushes via the ring-opening reaction of the epoxide groups with the amine moieties of the enzyme. The resultant GOD-functionalized P(GMA) brushes, with the accompanying hydroxyl groups from the ring-opening reaction of the epoxide groups, serves as an effective spacer to provide the GOD with a higher degree of conformational freedom and a more hydrophilic environment. An equivalent enzyme activity above 1.6 units/cm2 [micromoles of beta-D-(+)-glucose oxidized to d-gluconolactone per minute per square centimeter] and a corresponding relative activity of about 60% could be readily achieved. The immobilized GOD also exhibited an improved stability during storage over that of the free enzyme. The GOD-functionalized silicon substrates are potentially useful to the development of silicon-based glucose biosensors.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 119260.
authors.forename: F J
authors.initials: FJ
authors.lastname: Xu
authors.forename: Q J
authors.initials: QJ
authors.lastname: Cai
authors.forename: Y L
authors.initials: YL
authors.lastname: Li
authors.forename: E T
authors.initials: ET
authors.lastname: Kang
authors.forename: K G
authors.initials: KG
authors.lastname: Neoh
mesh_terms: D015374:Biosensing Techniques; D004800:Enzymes, Immobilized; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D011109:Polymethacrylic Acids / Q000737:chemistry; D012825:Silicon / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004800:Enzymes, Immobilized; D011109:Polymethacrylic Acids; C042535:polyglycidyl methacrylate; D005949:Glucose Oxidase; D012825:Silicon