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Biological electrode based on chitosan / clay composite build its sensing performance

Author: HanEn
Tutor: XueHuaiGuo；DanDan
School: Yangzhou University
Course: Physical and chemical
Keywords: Enzyme biosensor Response current Chitosan Hydrotalcite-like Hybrid materials Hemoglobin Enzyme electrode Electrode surface Layer-by-layer assembly Apparent Michaelis constant
CLC: O631.3
Type: Master's thesis
Year: 2008
Downloads: 124
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Abstract

Hemoglobin / Laponite / Chitosan Self assembly the direct electrochemical characteristics of the membrane electrode and hydrogen peroxide catalytic reduction sequentially through the layers of self-assembly method, the chitosan Laponite, hemoglobin fixed to the carboxyl group of the glassy carbon electrode surface preparation has become the high stability of the Hb / Laponite / CHT / GC electrode in order to achieve the direct electron transfer between hemoglobin and a glassy carbon electrode. Fixed scan rate 0.1Vs-1, control phosphate buffer pH 6.0, potential range of -0.8 ~ 0.8V, the self-assembled electrode cyclic voltammetry in approximately -0. 035V (vs. SCE) at the show one pair of stable, quasi-reversible redox peaks. This is from the hemoglobin heme Fe (III) / Fe (II) electrically on the occurrence of oxidation reduction reaction caused. Fixed in SAMs hemoglobin direct electrochemical reaction is controlled by a thin layer electrochemical process. Further, the form of standard potential of the group of heme attached Fe (III) / Fe (II) redox made change with the pH of the external solution (pH3.0 ~ 8.0) changes linearly, the slope of -63 mV pH -1, which indicates that an electron transfer in the electrochemical reactions, it is also accompanied by the transfer of a proton. UV spectrum, the hemoglobin Soret absorption peak did not move, fixed on the self-assembled film hemoglobin to keep its original secondary structure. Self-assembled electrode showed a better life, the use of 60 days but also to maintain its redox peak position is unchanged and remains 90% reduction peak current. The electrode also on hydrogen peroxide showed good catalytic reduction of linear detection range of 6.2 × 10-6 2.55 × 10-3M, when the signal-to-noise ratio of 3, the detection limit is 6.2 × 10 - 6M. The new high-sensitivity phenolic biosensor based chitosan / hydrotalcite hybrid materials research based on the study of the the chitosan / LDH hybrid materials new high sensitivity phenolic amperometric biosensors. The hybrid material has both a strong adsorption capacity of the inorganic clay-based hydrotalcite (LDH, Layered double hydroxides) and good hydrophilic properties, also has excellent properties of this biological polymer chitosan (Chitosan) amino polysaccharide easy film formation and good bio-compatibility characteristics. The results show that: the hybrid material can be provided as polyphenol oxidase good biological micro-environment, thus maintaining the basic characteristics of its original structure and its biological activity, to extend the life of the biosensor hybrid membranes were characterized by FT-IR . The results show that: the class hydrotalcite and chitosan mass ratio of 4:1; ratio of the hybrid film showed the best characteristics of the hydrophilic. The biosensor of catechol exhibit fast response characteristics Bioelectrochemical (5s can reach 95% of the maximum of the response current), the lower detection limit (0.36 nm), a wide linear detection range (3.6 × 10 -9 ~ 4 × 10-5M) and a high detection sensitivity (2750 ± 52 mA M-1 cm-2). The sensor the apparent Michaelis constant (KMapp) 0.13 mM. The activation energy of the enzyme-catalyzed reaction is 27.6 kJ mol-1. The same time, the biosensor showed a better life. Embedded in class hydrotalcite / chitosan inorganic-organic hybrid materials glucose oxidase biosensor using chitosan / hydrotalcite (LDH, Zn3-Al-Cl) hybrid materials immobilization of glucose oxidase (GOD ) was prepared to become a chitosan / LDH / GOD / Pt electrode. Experiment to find the optimum conditions for production of glucose oxidase biosensors, that the optimal ratio between the chitosan and LDH is 2:1, also studied the influence of the film thickness as well as the amount of enzyme used on the sensor response current. The study found the sensor using the best conditions for: measuring temperature of 50oC, working potential of 0.6V, substrate solution of pH 6.5. Meanwhile, study of the sensor under optimal experimental conditions, the response characteristics of the glucose solution. Experimental results show that: the biosensor to glucose showed a wide linear detection range (0.001 to 10 mM), the apparent Michaelis constant of the enzyme-catalyzed reaction 17.3mM, enzyme-catalyzed reaction apparent activation energy of 22.1 KJ. The sensor also showed a fast response, good reproducibility advantages.

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