Construction And Electrochemical Sensing Of Cyclodextrin Modified Carbon Based Materials

Electrochemical sensors have attracted wide attention due to their low cost,portability,rapid analysis and high selectivity.Designing an excellent electrode material is the key to improving the sensitivity and selectivity of electrochemical sensors.As an important class of supramolecular compounds,cyclodextrin is widely used in biomedicine and other fields due to its molecular selective recognition and supramolecular assembly.In this thesis,cyclodextrin is used as a functional unit to form an electrochemical sensor by covalent or non-covalent bonding of carbon-based materials such as graphene and porous carbon with superconductivity to achieve detection of different amino acids.The major contents of this thesis are as follows:1.The graphite oxide is synthesized by the modified Hummers method,then the graphene oxide and the 6-dexy-6-ethy-lenediamine-?-cyclodextrin are subjected to cyclic amination reaction,and then reduced by ascorbic acid to obtain a covalently bonded graphene cyclodextrin conjugate.The resulting conjugates were characterized using UV-vis spectroscopy,Fourier-transform infrared spectroscopy(FTIR).Raman spectroscopy,thermogravimetric analysis(TGA),X-ray diffraction(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).Subsequently,for the comparative study,glass carbon electrode electrochemical sensors modified with these conjugates were prepared to detect four structurally similar analytes(tyramine,L-tyrosine,dopamine and levodopa).By comparing the different modified electrodes and their sensing effects on different substrates,we found that compared with the bare electrode,the sensitivity of the graphene cyclodextrin modified electrode has been significantly improved,and the sensing effect of the electrode on different substrates.has a difference.Therefore,from the results of comparative studies,we can speculate that the main factors affecting the performance of the electrode including the binding affinity and the binding orientation of CD toward analytes.The conclusions drawn in this study could provide theoretical foundation for the design and optimization of versatile electrochemical platforms with excellent properties.2.Macroporous carbon was prepared by Ryoo method,and sulfato-?-cyclodextrins macroporous carbon hybrid was constructed by embedding sulfato-?-cyclodextrins into macroporous carbon by non-covalent bonding.And Fourier transform infrared spectroscopy,Thermogravimetric analysis,scanning electron microscopy and transmission electron microscopy were performed to characterize this hybrid.Then,the supramolecular assembly was used to construct an electrochemical sensor,and its specific recognition of the D-,L-tyrosine enantiomer was studied by differential pulse voltammetry.By comparing the sensor results,the cyclodextrin porous carbon modified electrode has a good current response to D-tyramine.3.Graphene aeroge was synthesized by sol-gel method,and then embedded the?,?,?-cyclodextrin into the graphene aerogel by non-covalent bond to construct the supramolecular assembly.Fourier-transform infrared spectroscopy,thermogravimetric analysis,scanning electron microscopy and transmission electron microscopy were used for characterization.Next,the supramolecular assembly was used to construct an electrochemical sensor,and differential voltammetry was used to detect the substrate molecule.