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

• Published in: Biomacromolecules 2005-03, Vol.6 (2), p.1012-1020
• Main Authors: Xu, F. J, Cai, Q. J, Li, Y. L, Kang, E. T, Neoh, K. G
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and medical sciences; Biosensing Techniques; Biotechnology; Enzymes, Immobilized; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Glucose Oxidase - chemistry; Glucose Oxidase - metabolism; Immobilization of enzymes and other molecules; Immobilization techniques; Kinetics; Methods. Procedures. Technologies; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Polymethacrylic Acids - chemistry; Preparation, kinetics, thermodynamics, mechanism and catalysts; Silicon - chemistry; Surface Properties
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm0493178

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 [μmoles of β-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.