Organic-Inorganic Hybrid Materials And Nano Materials Immobilized Enzyme Eletrochemical Biosensor

Electrochemical biosensor is one of the important research analytical chemistry of today's and sensor technology and measurement science, mainly in environmental monitoring, biomedical, food analysis and other fields. Sensing material and film of the enzyme method of constructing is a key of the development of excellent performance electrochemical biosensor. Organic- inorganic hybrid materials based on Sol-gel because of its series of advantages, which are as ideal biological molecule fixed material. In this paper, synthetic organic-inorganic hybrid materials fixed hemoglobin, horseradish peroxidase, glucose oxidase developed new biosensors. The electrochemical properties was studied, analytical methods was established, of the relevant regular was investigated and so on.This paper consists of the following parts:A novel hydrogen peroxide biosensor has been fabricated based on Hb entrapped poly (vinyl alcohol) (PVA)/Titanium dioxide (TiO₂) hybrid material. Multi-walled carbon nanotubes (MWCNTs) were then dispersed into the composite matrix. It was found that such hybrid material could retain the native biocatalytic activity of the entrapped Hb by electrochemical experiments. In addition, MWCNTs enhanced catalytic performance of hydrogen peroxide and promoted electronic transfer. Effects of some experimental variables such as the amount of MWCNTs, concentration of enzyme, amounts of modifier on the current response of the biosensor were investigated. A linear calibration graph was obtained in the concentration range of H2O2 from 5.0×10^-7 mol/L～2.7×10^-6 mol/L (linear regression coefficient 0.997) with a detection limit of 1.0×10^-7 mol/L (S/N = 3). The apparent Michaelis-Menten constant Km was 0.997×10^-6 mol/L. The biosensor displayed excellent repeatability, high sensitivity, long-term stability, and good selectivity. The recovery of H₂O₂ in samples was testified with satisfactory results.A new type of organic-inorganic material was developed by sol-gel process and used for the fabrication of hydrogen peroxide biosensor. Multi-walled carbon nanotube (MWCNTs) and copper nanoparticles were then dispersed into the composite matrix. By electrochemical experiments, it was found that such hybird material could retain the native biocatalytic activity of the entrapped hemoglobin. In addition, the synergistic effects of carbon nanotubes and copper nanoparticles enhanced catalytic performance of hydrogen peroxide and promoted electronic transfer. H₂O₂ could be determined in a linear calibration range from 1.0×10^-7 mol/L to 1.35×10-4 mol/L with a correlation coefficient of 0.9971 and a detection limit of 1.0×10^-8 mol/L at S/N ratio = 3. Apparent Michaelis-Menten constant (Km) as 12.83×10^-6 mol/L .A highly-sensitive biocomposite bienzyme biosensor was fabricated by entrapping glucose oxidase (GOx) and horseradish peroxidase (HRP) in Poly (vinyl alcohol)/Titanium dioxide PVA/TiO₂ hybrid materials immobilized on multi-walled carbon nanotubes and nanocopper modified glassy carbon electrode. Such a hybrid material could retain the native biocatalytic activity of the entrapped GOD and HRP. In addition, the synergistic effects of carbon nanotubes and copper nanoparticles enhanced catalytic performance of glucose and promoted electronic transfer. The excellent electrocatalytic activity of the biocomposite film resulted in the detection of glucose under reduced over potential with a wider range of determination from 6.2×10^-8 mol/L to 1.0×10^-6 mol/L (linear regression coefficient =0.998) and with a detection limit of 1.0×10^-9 mol/L (S/N = 3). The apparent Michaelis-Menten constant K_m was 0.037×10^-6 mol/L. Analytical performance in terms of high sensitivity, good selectivity, reproducibility and stability.ZnO nanorods were synthesized by microemulsion-based hydrothermal method and the highly efficient H₂O₂ biosensor was fabricated on the basis of the complex films of hemoglobin (Hb), ZnO nanorods, polyvinyl alcohol (PVA) dispersed solution. Biocompatible ZnO-PVA composition provided a suitable microenvironment to keep Hb bioactivity (Michaelis-Menten constant of 0.0019×10^-6 mol/L). The electrochemical behaviors and effects of solution pH values were carefully examined in this paper. The Hb-ZnO/PVA biosensor demonstrated excellently electrocatalytical ability for H₂O₂. This biosensor had a excellent linear relationships was obtained in the concentration range from 1.0×10^-8 mol/L to 3.2×10^-6 mol/L with the detection limit of 0.009×10^-6 mol/L (S/N=3) under the optimum conditions. Moreover, the stability and reproducibility of this biosensor were evaluated with satisfactory results. The chemically modified electrode of nafion multi-walled carbon nanotube (MWCNTs) functionalized with carboxylic group coated glassy carbon electrode (GCE/Nafion-MWCNTs) has been prepared. The electrochemical behavior of 2, 4-dinitro-1-naphthol and its electroanalytical method has been studied. In 0.025 mol/L Michaelis (pH 6.7) buffer solution, GCE/Nafion-MWCNTs exhibited a remarkable catalytic and enhanced effect on the current response of 2, 4-dinitro-1-naphthol. The reduction peak potential of 2, 4-dinitro-1-naphthol shifted positively from -0.710 V at bare GCE to -0.370 V at GCE/Nafion- MWCNTs, and the sensitivity increased 3 times. The reduction peak current was enhanced greatly on the GCE/ Nafion-MWCNTs. Some experimental conditions were optimized. The result of linear calibration range for 2, 4-dinitro-1-naphthol was from 1.0×10^-8 mol/L to 2.0×10^-5 mol/L, ip/(μA) =2.248+0.87 c (10^-6 mol/L) (R =0.9975) with a detection limit of 1.0×10^-9 mol/L. The method has been used to determine the concentration of 2, 4-dinitro-1-naphthol in samples with the recovery ranging from 97.10 % to 101.3 %.