Electrochemical Biosensing Based On Biological Macromolecule Modified Electrodes

Electrobiosensing technology is considered to be a promising analyticalmethod, which is due to its low cost, high sensitivity and easily miniaturization andautomation. In this paper, Glassy carbon electrode （GCE） were modified as enzymesensors to determine glucose; Au electrode were modified as DNA damage sensorsand immunosensors to determine aflatoxin B₁.This thesis includes:1. Direct electrochemistry of glucose oxidase immobilized on macroporousordered silica foam modified glassy carbon electrodeGlucose oxidase@Macroporous ordered silica foam modified GCE wereprepared with optimum concentration of optimal PBS pH7.0, the best modificationconcentration of Glucose oxidase was550U mL^-1,and the best modification amountof Macroporous ordered silica foam was7μg. i-t curves was used to make theglucose calibration curve: i （μA）=3.205C+1.067, the correlation coefficient Rwas0.999,the linear detection range was from50¹850μmol L^-1，the apparentMichaelis-Menten constant for glucose was2.073mmol L^-1.2. AFB₁biosensor based on aAFB₁@AuNPs/AuHere, a rapid method for AFB₁was designed by Au electrode modified byaAFB₁@AuNPs as an electrochemical biosensor. Impedance spectrums、cyclicvoltammetry and Differential Pulse Voltammetry were used to characterize theelectrochemical response of AFB₁at Au electrode, and investigate the optimalconditions, such as modified AFB₁by4℃、8h, the pH value of PBS is7.4. Underthe optimized conditions, calibration curve: i （μA）=0.02166C+18.8682, thelinear correlation coefficient R=0.9997; the linear range is1.427¹50ng mL^-1.The biosensor was used to determine several pig diets samples successfully whichrecoveries was from94.44%to101.36%.3. AFB₁biosensor based on ssDNA modified Au electrodePreparing an AFB₁biosensor based on ssDNA modified Au electrode with MBas indicator. ssDNA/Au was prepared as following: using–SHssDNA assembled 12h,and then, soaking in AFB₁solutions500s. The concentration of MB was3.0×10^-5 mol L^-1, and the pH value of Tris-HCL buffer solutions was8.5. Thestandard curve for i （μA）=-0.00059C+0.3299, the linear correlation coefficient R=0.9942, and the limit detection was9.7ng mL^-1.