Covalent Immobilization of Glucose Oxidase on Well-Defined Poly(glycidyl methacrylate)-Si(111)Hybrids from Surface-Initiated Atom-Transfer Radical Polymerization

摘要

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/cm~2)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/cm~2 [mumoles 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.