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Amperometric Enzyme Biosensors Based On Nanocomposites

Posted on:2013-09-21Degree:MasterType:Thesis
Country:ChinaCandidate:H A ZhongFull Text:PDF
GTID:2231330371471343Subject:Analytical Chemistry
Abstract/Summary:PDF Full Text Request
Since the development of the first glucose biosensor in1962. the enzyme biosensors have attracted much attention and widely applied in various fields including clinical medicine, food, environmental, industrialand nearly half a century, because of its wide linear range, high sensitivity, low detection limit, good selectivity and low cost.A variety of nano-materials has been applied to fabricate the enzyme biosensor due to its surface and interface effect, small size effect, quantum size effect, macroscopic quantum tunneling effect. Nano-materials have good biocompatibility and can maintain the activity and stability of the protein molecules, they also have large surface area can increase the protein molecules of the solid load. Based on the above considerations, the main research works in this paper had constructed horseradish peroxidase, glucose oxidase, cholesterol oxidase enzyme biosensor using a variety of nano-composites, there have a great improvement on the performance such as detection limit, sensitivity, selectivity and stability.The main works are included as follows:1. Amperometric biosensor for hydrogen peroxide based on horseradish peroxidase onto gold nanowires and TiO2nanoparticlesAn electrochemical biosensor for determination of hydrogen peroxide (H2O2) was developed, based on the immobilization of horseradish peroxidase (HRP) with one-dimensional gold nanowires (Au NWs) on a gold electrode modified with TiO2nanoparticles (nano-Ti02) via electrostatic interactions. The nano-TiO2can give a biocompatible microenvironment and compact film, and the Au NWs can provide fast electron transferring rate and greatly add the amount of HRP molecules immobilized on the electrode surface. Au NWs were characterized by ultraviolet-visible (UV-Vis) spectra and transmission electron microscope (TEM). The electrode modification process was probed by cyclic voltammetry and electrochemical impedance spectroscopy. Chronoamperometry was used to study the electrochemical performance of the resulting biosensor. The synergistic effect of Au NWs and nano-TiO2made the biosensor exhibit excellent electrocatalytic activity and good response performance to H2O2. Under optimal conditions, the linear range for the determination of H2O2was from2.3μmol·L-1to2.4mmol·L-with a detection limit of0.7μmol·L-1at a signal-to-noise ratio of three. Moreover, the proposed biosensor showed superior stability and high sensitivity.2. In situ chemo-synthesized multi-wall carbon nanotube-conductive polyaniline nanocomposites:Characterization and application for a glucose amperometric biosensorA new glucose amperometric biosensor, based on electrodeposition of platinum nanoparticles onto the surface of multi-wall carbon nanotube (MWCNT)-polyaniline (PAN1) nanocomposites, and then immobilizing glucose oxidase (GOD) with covalent interaction and adsorption effect, was constructed in this paper. Firstly, the MWNT-PANI nanocomposites had been synthesized by in situ polymerization and were characterized through transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and ultraviolet and visible (UV-Vis) absorption spectra. The assembled process of the modified electrode was probed by scanning electron microscopy (SEM) and cyclic voltammetry (CV). Chronoamperometry was used to study the electrochemical performance of the resulting biosensor. The glucose biosensor exhibited a linear calibration curve over the range from3.0μmol·L-1to13.5mmol·L-1, whit a detection limit of1.0μmol·L-1and a high sensitivity of12.6μA·L-mmol-1. The biosensor also showed a short response time (within5s). Furthermore, the reproducibility, stability and interferences of the biosensor were also investigated.3. Fabrication of multi-walled carbon nantube-polyaniline/platinum nanocomposite films towards improved performance for a cholesterol amperometric biosensorA simple and highly sensitive cholesterol amperometric biosensor, based on in situ electropolymerization multi-wall carbon nanotubes-polyaniline nanocomposite (MWCNT-PANI) and electrodeposited platinum nanoparticle (Pt) films onto the surface of glassy carbon electrode, and then immobilizing cholesterol oxidase with covalent interaction and adsorption effect, was constructed in this paper. The preparation process of the modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, and chronoamperometry. Because of the synergistic electro-catalytic activity between MWCNT-PANI nanocomposites and Pt, the cholesterol biosensor exhibited excellent performance with a linear range of2.0μmol·L-1to510.0μmol·L-1, a detection limit of0.8μmol·L-1(S/N=3), a high sensitivity of109.9μA·L·μmol-1, and a short response time within5s. Moreover, the reproducibility, stability and selectivity of the biosensor were also investigated.
Keywords/Search Tags:Biosensor, Horseradish peroxidase, Glucose oxidase, cholesterol oxidase, Gold nanowire, Carbon nanotube, Polyaniline
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