Glucose biosensor based on the room-temperature phosphorescence of TiO 2/SiO 2 nanocomposite

Abstract

The direct immobilization of glucose oxidase (GOD) on TiO 2/SiO 2 nanocomposite and its application as glucose biosensor were investigated. The room-temperature phosphorescence of TiO 2/SiO 2 nanocomposite can be quenched by hydrogen peroxide (H 2O 2). The detection of glucose may be accomplished by monitoring the formation of hydrogen peroxide which generated in the oxidation process of glucose with the catalysis of GOD. To our surprise, by using a 96-hole polyporous plate accessory of fluorescence spectrophotometer, the biosensor exhibits excellent linear response to glucose concentrations ranging from 1.0 × 10 −9 to 1.0 × 10 −2 M with a detection limit of 1.2 × 10 −10 M. The TiO 2/SiO 2 nanocomposite can be used as both supporting material and signal transducer. The phosphorescence intensity and color of the biosensor change obviously and even could be observed with naked eyes by continuous addition of glucose. Based on the room-temperature phosphorescence of TiO 2/SiO 2 nanocomposite, a new method of solid substrate-room-temperature phosphorimetry (SS-RTP) for glucose determination is proposed. A glucose biosensor was fabricated with wide determination concentration range, low detection limit, high sensitivity, and fast response time. And the biosensor has been successfully applied to the determination of glucose in human blood serum. The coacervation of GOD enzyme and its interaction with TiO 2/SiO 2 nanocomposite enlarge the surface area and enhance the chemical stability of GOD. The nice biocompatibility, large surface area, good chemical stability and nontoxicity of the TiO 2/SiO 2 nanocomposite have made this material suitable for functioning as biosensor.