Novel Glucose Oxidase Electrode For Electrochemical Detection Of Glucose In Honey

Glucose oxidase（GOx）,as a molecular recognition element of glucose biosensors,has the advantages of high sensitivity and high selectivity.In recent years,with the development of nanotechnology,the conductivity and specific surface area of nanomaterials have been focused to improve the performance of GOx biosensors.However,the method to change GOx’s own structure to improve the performance of the biosensor has been neglected.In this study,the surface of GOx was rapidly modified by small molecule chemical modification technology to obtain a modified new enzyme（mGOx）.At the same time,in order to improve the dispersion performance of the material in the solution and enhance the enrichment effect of the substrate,β-cyclodextrin（β-CD）was introduced into the carbon nanomaterial multi-walled carbon nanotubes（MWCNTs）to obtain the compositeβ-CD/MWCNTs.Finally,composite materialswere used as mGOx carriers to improve the performance of mGOx biosensors.The main research content and experimental results of the thesis are as follows:（1）Firstly,GOx was rapidly modified by small molecule surface chemical modification technology,and 1-carboxymethyl-3-methylimidazole bis（trifluoromethanesulfonyl）imide salt was covalently attached to GOx molecules to obtain mGOx,and then mGOx and MWCNTs were loaded on the glassy carbon electrode（GCE）,and finally the mGOx/MWCNTs/GCE biosensor was obtained.Circular dichroism and infrared spectroscopy（FTIR）were used to characterize the material changes during the electrode preparation process,and the electrochemical properties of the modified electrode in glucose solution were studied by cyclic voltammetry and time-current method.The results showed that the biosensor had a wide linear range（50μM～3 m M）,a low glucose detection limit（0.58μM）,and a sensitivity of 23.3μA·m M^-1cm^-2.At the same time,the biosensor had excellent selectivity,storage stability（97%current retention within two weeks）and repeatability（n=10,RSD=2.8%）.The glucose in the actual sample of honey was detected,and the RSD of the sensor was found below 2.69%.（2）In order to improve the dispersion performance of multi-walled carbon nanotube carrier materials in solution and enhance the enrichment effect of substrates,β-CD and MWCNTs were combined to prepareβ-CD/MWCNTs composite carrier materials;Then,GOx was loaded on theβ-CD/MWCNTs composite material to construct a new type of biosensor GOx/β-CD/MWCNTs/GCE.the formation ofβ-CD/MWCNTs and the successful immobilization of GOx on theβ-CD/MWCNTs carrier were confirmed by Scanning electron microscopy（SEM）and FTIR.The results showed that the linear range of the biosensor was quite wide（50μM～1.15 m M）,the detection limit was low（0.42μM）,and the sensitivity was32.28μA·m M^-1cm^-2.At the same time,GOx/β-CD/MWCNTs/GCE biosensor had good anti-interference,storage stability（current retention of 95.7%within two weeks）and repeatability（n=10,RSD=2.5%）.The glucose in the actual sample of honey was detected,and it was found that the RSD of the sensor was below 2.04%.（3）Based on the integrated effect of modified enzymes and composite carrier materials to enhance sensor performance,the modified glucose oxidase mGOx was loaded onβ-CD/MWCNTs composite materials to construct a new biosensor mGOx/β-CD/MWCNTs/GCE.Characterization of SEM and FTIR confirmed that mGOx was successfully immobilized onβ-CD/MWCNTs carrier.The results showed that the prepared sensor could sensitively detect glucose with a detection range of 50μM～1.15 m M,a sensitivity of 35.44μA·m M^-1cm^-2,and a detection limit as low as 0.27μM.In addition,the biosensor had good stability（95.8%current retention within two weeks）,reproducibility（n=10,RSD=1.6%）and anti-interference.Experiments on actual samples showed that the glucose biosensor could be successfully applied to the detection of glucose in honey.