Electrochemical Sensor Of Food Polyphenols Based On Cyclodextrin Hybrid Materials

Compared with other common analytical and measurement methods,electrochemical sensors play an important role in environmental monitoring,food,medicine and other fields due to their advantages of high sensitivity,fast response,simple operation,easy integration and automation.The performance of electrochemical sensors is usually determined by the performance of electrode modified materials.With the increasing application scenarios of electrochemical sensors and the continuous improvement of their detection performance requirements,it is difficult to meet the needs of sensors constructed by single material modified electrodes.Therefore,it is of great significance to explore electrode modified materials with higher recognition performance and better stability to promote the development of electrochemical sensors.Cyclodextrin is a kind of natural polysaccharide macromolecule with hydrophobic inside and hydrophilic outside circular frustum cavity structure,which has excellent molecular recognition ability,affinity and strong adsorption capacity.By modifying its surface,introducing other groups（-SH,-NH₂,-COOH,etc.）or mixing with other materials,it can improve its own defects and give it more characteristics,making it suitable for the construction of electrochemical sensors.In this paper,based on cyclodextrin and its modified and modified derivatives,and based on the affinity between cyclodextrin and phenols,several new sensors were constructed for the detection of dietary polyphenol compounds.The specific contents are as follows:1.rGO-CD was prepared by one-pot method,and then recombined with graphene quantum dots（GQDs）to form rGO-CD/GQDs composite material with good electrical conductivity and stability.The rGO-CD/GQDs composite material was drip-coated on glassy carbon electrode（GCE）,dried,and electrodeposited MoO₃ nanorods on the surface of modified electrode.A novel electrochemical sensor was developed for the determination of quercetin.MoO₃ nanorods can be uniformly distributed on the electrode surface by means of electrodeposition,giving full play to its catalytic performance.The modified electrode showed a wide linear range（5 n M-2600 n M）for quercetin.The sensor can also be used to detect quercetin in real samples（fruit juices）.2.Cyclodextrin nanosponges（CDNS）were prepared by a simple and rapid method.After being combined with graphene quantum dots（GQDs）and acidified multi-wall carbon tubes（MWCNTs-COOH）,a catechin（Cat）electrochemical sensor was constructed.CDNS can achieve good enrichment of Cat by using the cavity,intermolecular gap and surface active groups of CD molecules.The excellent biocompatibility of GQDs and the excellent electrocatalytic activity and good stability of MWCNTs-COOH can improve the defect of low conductivity of CDNS,and the three factors play a synergistic role to achieve a rapid detection of Cat.The peak current of CDNS/GQDs/MWCNTs-COOH/GCE response to catechins was linear between 20n M and 1200 n M,The detection limits was 4.45 n M.3.MoO₃ nanorods were synthesized by chemical method,and then bonded with 3,4-ethylenedioxythiophene（EDOT）to form MoO_3-poly（3,4-ethylenedioxythiophene）（MoO₃-PEDOT）and drip-coated on GCE.Finally,theγ-cyclodextrin metal-organic framework（CD-MOF-1）was electrodeposited on the surface of the modified electrode.A highly sensitive electrochemical sensor was developed for the detection of luteolin.The microstructure and internal composition of the materials were analyzed by means of XRD,SEM and XPS.Due to the excellent electron conduction ability of PEDOT,MoO₃ combined with it can improve the stability of the polymer,while CD-MOF contains a large number of hydroxyl groups,which has a good ability to recognize flavonoids.With these characteristics,the sensor shows a wide linear range of 0.4-1800n M and a low detection limit of 0.1 n M.The interference of citric acid,chlorogenic acid,luteolin and some common metal ions could be ignored to some extent.Finally,the sensor was applied to detect luteolin in real samples.