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Development and applications of electrochemical biosensors
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Type
Thesis
Author
Li, Juan
Supervisor
Tan, Swee Ngin
Abstract
This dissertation is devoted to the development of electrochemical biosensors prepared via the sol-gel immobilisation technique. Certain biosensors have been adopted as detectors in a flowing cell for flow injection analysis (FIA).
Chapter 1 is an introduction to some fundamental concepts, working principle, classification and applications of biosensors, and electrochemical biosensors. Enzyme electrodes as a branch of biosensors are discussed in detail with respect to enzyme kinetics, immobilisation techniques and their characterisation.
Chapter 2 is to explain the theory and methodology used in the work. Sol-gel technique, electrochemical techniques including cyclic voltammetry and amperometry, and FIA technique are described in detail. Literature relevant to the sol-gel matrix as an immobilisation matrix for protein molecules is reviewed as much as possible.
In Chapter 3, a glucose biosensor based on oxygen electrode has been prepared by entrapping the glucose oxidase (GOD) in the sol-gel matrix supported on a nylon membrane and fixing the membrane over the measuring section of the oxygen electrode. This simple glucose biosensor has given a good linear calibration curve and stability.
In Chapter 4, a glucose biosensor based on carbon paste electrode (CPE) has been developed via the sol-gel technique in a new "sandwich" configuration: CPE: sol-gel-ferrocene:GOD:sol-gel. The parameters affecting the performance of the glucose biosensor have been studied systematically. Cyclic voltammetry and amperometry measurements have been used to study the response of the glucose biosensor. The application of the biosensor has been demonstrated based on FIA system on soft drink samples.
In Chapter 5, a surface renewable bulk modified glucose biosensor has been developed based on the sol-gel technique. Organic modified silica sol-gel has been used as starting precursor to impart hydrophobicity for the electrode. The fabrication and characterisation of the bare silica sol-gel carbon electrode and silica sol-gel derived carbon glucose biosensor have been studied by changing some important experimental parameters in the stock sol-gel solution. The renewable biosensor has shown a very good stability and also reproducibility.
In Chapter 6, an amperometric biosensor for hydrogen peroxide in aqueous phase has been developed via the sol-gel technique. The biosensor comprised horseradish peroxidase (HRP) immobilised by the thin silica sol-gel film on CPE. Hydrogen peroxide has been detected in the presence of ferrocyanide as a mediator to transfer electrons between the electrode surface and hydrogen peroxide. The resulting biosensor has been proven to be a good detector for FIA.
Chapter 7 demonstrates for the first time the possibility of using the sol-gel modified HRP enzyme electrode for the detection of peroxides in organic phase. The effect of operating parameters, such as types of organic solvents, the amount of aqueous buffer in organic solvent, etc. have been explored for the optimum analytical performance of the biosensor. The biosensor has shown excellent stability in some organic solvents, including methanol, acetonitrile and 2-propanol.
Chapter 8 describes a phenolic compounds biosensor which comprised tyrosinase immobilised by the thin sol-gel film on CPE. Phenolic compounds have been determined directly by the reduction of biocatalytically liberated quinone species at 0 mV vs. Ag/AgC1(sat.KC1). The sensitivity for catechol, phenol, p-cresol, m-cresol, o-cresol and 2-chlorophenol were 1.45, 1.28, 1.03, 0.64, 0 and 0 A M-1 respectively.
Chapter 1 is an introduction to some fundamental concepts, working principle, classification and applications of biosensors, and electrochemical biosensors. Enzyme electrodes as a branch of biosensors are discussed in detail with respect to enzyme kinetics, immobilisation techniques and their characterisation.
Chapter 2 is to explain the theory and methodology used in the work. Sol-gel technique, electrochemical techniques including cyclic voltammetry and amperometry, and FIA technique are described in detail. Literature relevant to the sol-gel matrix as an immobilisation matrix for protein molecules is reviewed as much as possible.
In Chapter 3, a glucose biosensor based on oxygen electrode has been prepared by entrapping the glucose oxidase (GOD) in the sol-gel matrix supported on a nylon membrane and fixing the membrane over the measuring section of the oxygen electrode. This simple glucose biosensor has given a good linear calibration curve and stability.
In Chapter 4, a glucose biosensor based on carbon paste electrode (CPE) has been developed via the sol-gel technique in a new "sandwich" configuration: CPE: sol-gel-ferrocene:GOD:sol-gel. The parameters affecting the performance of the glucose biosensor have been studied systematically. Cyclic voltammetry and amperometry measurements have been used to study the response of the glucose biosensor. The application of the biosensor has been demonstrated based on FIA system on soft drink samples.
In Chapter 5, a surface renewable bulk modified glucose biosensor has been developed based on the sol-gel technique. Organic modified silica sol-gel has been used as starting precursor to impart hydrophobicity for the electrode. The fabrication and characterisation of the bare silica sol-gel carbon electrode and silica sol-gel derived carbon glucose biosensor have been studied by changing some important experimental parameters in the stock sol-gel solution. The renewable biosensor has shown a very good stability and also reproducibility.
In Chapter 6, an amperometric biosensor for hydrogen peroxide in aqueous phase has been developed via the sol-gel technique. The biosensor comprised horseradish peroxidase (HRP) immobilised by the thin silica sol-gel film on CPE. Hydrogen peroxide has been detected in the presence of ferrocyanide as a mediator to transfer electrons between the electrode surface and hydrogen peroxide. The resulting biosensor has been proven to be a good detector for FIA.
Chapter 7 demonstrates for the first time the possibility of using the sol-gel modified HRP enzyme electrode for the detection of peroxides in organic phase. The effect of operating parameters, such as types of organic solvents, the amount of aqueous buffer in organic solvent, etc. have been explored for the optimum analytical performance of the biosensor. The biosensor has shown excellent stability in some organic solvents, including methanol, acetonitrile and 2-propanol.
Chapter 8 describes a phenolic compounds biosensor which comprised tyrosinase immobilised by the thin sol-gel film on CPE. Phenolic compounds have been determined directly by the reduction of biocatalytically liberated quinone species at 0 mV vs. Ag/AgC1(sat.KC1). The sensitivity for catechol, phenol, p-cresol, m-cresol, o-cresol and 2-chlorophenol were 1.45, 1.28, 1.03, 0.64, 0 and 0 A M-1 respectively.
Date Issued
1998
Call Number
R857.B54 Li
Date Submitted
1998