| Glucose oxidase (GOD) has been widely applied in pharmaceutical, food andbiological industries because of its strong specificity, high activity and catalytic efficiencyand warmly. And also GOD, one of the earliest studies of the enzyme biosensor, play aimportant role in food analysis, fermentation control, clinical testing. Currently we knowglucose oxidase biosensor still remain easy missing enzyme, poor of repeat stability andstorage stability, vulnerable to interference of outside noise. This paper aims to selectefficient electrode modified material, research on the performance of the efficientmodification modified electrode material preparing glucose oxidase biosensor, make thehigh sensitivity of the glucose oxidase biosensor; And to explore the enzyme modifiedelectrode material impact on the nature and structure of glucose oxidase, to improve thisproblem, this thesis contents and results are as follows:1. With ferricyanide redox probe, gold nanoparticles modified material selected,using cyclic voltammetry contrast CHIT/AuNPs and Cys/MWCNTs/Au combinationof two different materials, Because Cys/MWCNTs/Au current response higher than theformer, prove that sensitivity is good, so choose the latter for the final modified material.2. Taking Cys/MWCNTs/AuNPs electrode material for the preparation ofglucose oxidase biosensor and built glucose oxidase biosensor, to optimize the preparationconditions of the sensor. Made the current value as the evaluation, study of the reactionsystem, mainly include the optimum pH, optimum temperature, optimum amount ofglucose oxidase solid carrier, the optimum reaction time. The result show that optimizedpH is6.0, temperature is40℃, best glucose oxidase solid load is16U, best reaction timeis20s. But the condition of glucose oxidase biosensor applications is at room temperature,so finally choose25℃.3. After that, glucose oxidase biosensor properties including permeability of thebiosensor, response to different concentrations of glucose, the test of sensor interference,repetition stability and storage stability of the sensor is experiments were investigated. Theresult show that biosensor has good permeability, for0-12mmol/L glucose concentrationis linear, linear equation is I=0.046c+8.9258, r2=0.9922, the detection limit is1×10-6.Glutathione has little effect on the sensor, but the interference of ascorbic acid is large.Repeat stability is good, the relative standard deviation of six times is0.941%; and storagestability of the sensor is better, after14days, response current decreased2.77%, does notexceed10%of the initial current, so description good storage stability. 4. The enzymatic properties and the structure activity of glucose oxidasemodified were studied. The results showed that glucose oxidase modified with AuNPs inbiological activity is improved; The same optimum pH of the modified glucose oxidase ispH6.5,the same with unmodified glucose oxidase; Insulation after24h and72h, the activityof AuNPs in glucose oxidase solution were higher than the unmodified glucose oxidase, itmeans that pH stability compared to the unmodified enzyme glucose oxidase good; Theoptimum temperature of AuNPs and glucose oxidase are the same is40℃; At60℃and70℃insulation5h, glucose oxidase modified by AuNPs has lower activity thanunmodified glucose oxidase enzyme, it means that temperature stability compared to theunmodified enzyme glucose oxidase was poor. By circular dichroism studing thesecondary structure of modified and unmodified of glucose oxidase, the study found thatthe helix of the modified glucose oxidase content are increasing in α helix; by fluorescencespectroscopy study found that modified by AuNPs, glucose oxidase blue shift, glucoseoxidase structure more closely. |
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