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Study Of Biosensors Based On Sol-Gel Techniques And Nanoparticles

Posted on:2009-08-29Degree:MasterType:Thesis
Country:ChinaCandidate:J L JiangFull Text:PDF
GTID:2178360278971217Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
Since 1962, the first model of enzyme electrode has reported by Clark, development of biosensor was very fast. Assembly of biological molecules within a solid-state framework provides several unique advantages for design of biosensors. The main limitations in this direction have been a lack of an appropriate immobilization process and a matrix that can prevent denaturation of biomolecules. The sol-gel process provides extraordinary opportunities to integrate solution chemistry of molecular entities into a solid-state framework under mild conditions. The rigid sol-gel matrix not only restricts molecular motion and fixes these molecules in space, but also, by virtue of its framework, provides mechanical strength and improved long-term stability. The present research work focuses on the selecting and optimizing sol-gel materials, improving immobilizing methods, and designing several types of novel electrochemical sensor systems. The major content and results of this dissertation are summarized and described as follows.1. An Amperometric Glucose Biosensor Based on Titania Sol-Gel/Prussian Blue Composite FilmAn improved amperometric glucose biosensor was constructed by immobilizing glucose oxidase (GOD) in a titania sol-gel film, which was prepared by a vapor deposition method, on a Prussian blue (PB)-modified electrode. The method combined the merits of immobilizing biomolecules in the titania sol-gel film by vapor deposition method. Results showed that the fabricated titania sol-gel/PB membrane possessed high surface area, good mechanical stability, and good hydrophilicity, which provided a biocompatible microenvironment for maintaining the bioactivity of the immobilized enzyme and prevented the enzyme from leaking out of the film. Therefore, the present biosensor exhibited fast response time (10 s), high sensitivity (12.74μA mM-1 cm-2), long-term operational stability, good suppression of interference, and a wide linear range from 0.02 to 15 mM with a low detection limit of 5μM for the detection of glucose. 2. Preparation of MWCNTs/PB Composite Material Modified ElectrodeA new type of composite novel electrode was fabricated by incorporation of MWCNTs/PB composite material modified gold electrode with a vapor deposition method. The modified electrode showed excellent catalytic activity for hydrogen peroxide, which combined the merits of the synergic catalysis effects of PB and MWCNTs. In addition, glucose oxidase (GOD) was immobilized on MWCNTs/PB modified electrode, and the glucose biosensor exhibited fast response time and high sensitivity. This method could widen the application area of sol-gel and provide a commendable model system for research the synergic catalysis effects.3. Preparation of GOD/Sol-gel Silica Film on Prussian Blue Modified Electrode for Glucose Biosensor ApplicationA novel amperometric glucose biosensor was fabricated by in situ incorporating glucose oxidase (GOD) within the sol-gel silica film on a Prussian blue (PB) modified electrode. The method is simple and controllable, which combined the merits of in situ immobilizing biomolecules in sol-gel silica film by electrochemical method and the synergic catalysis effects of PB and GOD molecules. Scanning electron microscopy (SEM) showed that the GOD/sol-gel silica film was homogeneous with a large number of three-dimensional nanopores, which improved the stability and sensitivity of the biosensor. The FTIR and UV-vis spectrum indicate that GOD has been successfully incorporated into the sol-gel silica matrix and the secondary structure was maintained well. The fabricated GOD/sol-gel/PB biosensor showed fast response time, high sensitivity, long-term stability, good suppression of interference, and wide linear range to glucose concentration.4. Preparation of GOD/Sol-gel Silica Film on Pt NPs/MWCNTs Modified Electrode for Glucose Biosensor ApplicationA new type of composite nano-material modified electrode was constureted by electrochemical deposition of platinum nanoparticles onto MWCNTs modified platinum electrode. The modified electrode showed excellent catalytic activity for hydrogen peroxide, which combined the merits of the synergic catalysis effects of MWCNTs and platinum nanoparticles. In addition, sol-gel/GOD was immobilized on Pt NPs/MWCNTs modified electrode by electrochemical deposition, and the glucose biosensor exhibited fast response time. Experimental results indicate that high dispersed platinum nanoparticles on MWCNTs, which has large surface area, ehxibited a good electrocatalytical activity toward hydrogen Peroxide. The glucose biosensor which was base on adsorption of glueose oxidase at Pt NPs/MWNTs substance by using nanoparticles results in excellent sensitivity, low detection limit, large linear range, and good stability.
Keywords/Search Tags:sol-gel, biosensor, immobilized enzymes, electrochemical deposition, Prussian blue, glucose
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