Synthesis Of Cyclodextrin Functionalized Graphene Material And Its Application In Electrochemistry

Three-dimensional（3D）graphene is a new type of graphene material with porous network structure formed by the hybridization of carbon atoms with sp² and sp³.Compared with two-dimensional graphene,it not only recovers and inherits the inherent characteristics of graphene,but also has a larger specific surface area,stronger electrical conductivity,more active sites and other excellent properties on this basis,which has a broader application prospect in the fields of analysis sensing,catalysis,adsorption and other fields.However,3D graphene also has disadvantages such as poor water dispersion and weak stability.In order to improve its performance,it can be further modified by taking advantage of the increase of functional sites and the increase of the availability of its inner surface.In this study,β-cyclodextrin,γ-cyclodextrin and Pd metal nanoparticles were modified on3D graphene by one-step hydrothermal reduction method,respectively.Three different nanocomposites were synthesized,and the electrochemical detection of dopamine（DA）,5-hydroxytryptopine（5-HT）and ractopamine（RAC）was realized.The specific content is as follows:（1）Aβ-cyclodextrin modified three-dimensional reduced graphene oxide nanocomposite（3D-rGO/β-CD）has been successfully synthesized.According to modify the 3D-rGO/β-CD onto the surface of glassy carbon electrode（GCE）,an electrochemical sensor has been prepared for detection of dopamine（DA）.The result shows that the 3D-rGO/β-CD nanocomposite not only has the good electrical conductivity of three-dimensional graphene,but also has the host-guest recognition performance ofβ-CD.Differential pulse voltammetry（DPV）has been used to detect DA qualitatively and quantitatively with a wide linear range and a lower detection limit.It is proved thatβ-CD and DA could form an inclusion complex with an inclusion ratio of 1:1 by UV titration,and the inclusion constant is 178.8 M^-1.In addition,the sensor also has the advantages of high sensitivity and strong anti-interference ability,which provides a faster,simpler and more effective electrochemical detection method for DA.（2）Further,a 3D-rGO/γ-CD/GCE electrochemical sensing platform is successfully constructed by drippingγ-CD functionalized 3D-rGO on the surface of GCE,which is applied for the detection of serotonin（5-HT）.Because of the larger hydrophobic cavity ofγ-CD,it can be used to identify larger molecules.The results of the study found that 3D-rGO/γ-CD/GCE plays an excellent role in the recognition of 5-HT under the optimal experimental conditions,and there is linear relationships between the oxidation peak current of 5-HT and a certain range of concentration（0.5～75μM）.During the detection,it reveals outstanding anti-interference performance.At the same time,satisfactory results are obtained for the determination of 5-HT in serum samples.The ¹H NMR spectra further showed that there is a host-guest interaction betweenγ-CD and 5-HT,which provide the effective interaction for recognition of 5-HT by theγ-CD.Therefore,the electrochemical sensing platform provides a new detection approach for the identification and detection of larger molecules in environmental biomedicine.（3）Owing to inprove the catalytic performance of the sensor,an electrochemical sensor based on 3D-rGO/Pd/β-CD nanocomposites has been successfully constructed,which is further applied to detect ractopamine（RAC）.The sensor takes several advantages,such as the great electrochemical performance of 3D-rGO,high electrocatalytic performance of Pd NPs,and the specific recognition performance ofβ-CD,which displays a remarkable electrochemical detection capability with combination of these propretes.The study exhibits that the constructed sensor reveals a fine electrochemical response to RAC,showing two good linear relationships in the concentration range of 4～94μM.Furthermore,the inclusion ofβ-CD and RAC was demonstrated by ¹H NMR spectroscopy and UV titration with the inclusion ratio is 2:1.Meanwhile,the sensor has great reproducibility,high stability and strong anti-interference ability.The detection of RAC in pork samples has also achieved good results,which further expands the application of electrochemistry in environmental detection and analysis fields.