Assembly And Application Of Novel Electrochemical Sensors Based On Cyclodextrin Derivatives

As a representative of the second-generation supramolecular system,cyclodextrin?CDs?possess a hydrophobic inner cavity,a hydrophilic exterior surface and excellent inclusion of the guest molecules that match size of the cavity.Moreover,the hydroxy groups at the edge of the CDs cavity can form hydrogen bonds and undergo electrostatic and dipole-dipole.Therefore,CDs based materials drew widespread attention in electrochemical sensors.However,natural cyclodextrins have the disadvantage of monotonicity and low solubility,especially?-cyclodextrin.Moreover,?-cyclodextrin forms an unstable complex due to adhesion to the surface of the material only at one interface.Therefore,its application is limited.In recent years,the development of new ultra-sensitive electrochemical sensors based on cyclodextrin derivatives is an important direction of research.,Combining?-cyclodextrin derivatives and graphene,quantum dots and gold nanoparticles,several novel quercetin and amino acid electrochemical sensors were assembled from the perspective of economy,high sensitivity and effectiveness in this paper.1.Ultrasensitive quercetin electrochemical sensor based on 1-butyrate functionalized reduced graphene oxide/mercapto-?-cyclodextrin/gold nanoparticle composite membrane.PB-rGO/TCD/AuNPs nanocomposites were successfully synthesized by using gold nanoparticles as a linker.This material integrates the high molecular recognition ability of TCD and the high conductivity and specific surface area of PB-rGO/AuNPs.The electrochemical sensor obtained by modifying the glassy carbon electrode has an ultrasensitive sensitivity to quercetin.Under optimal conditions,quercetin has a linear response range of 0.005-0.4?M and a detection limit of 1.83 nM.At the same time,flavonoids with similar structures do not interfere with the determination of QR.In addition,the sensor has been applied to the detection of quercetin in apple juice,red wine and honeysuckle with satisfactory results.2.Electrochemical one-step preparation of aminated graphene quantum dot/full sulfhydryl?-cyclodextrin functionalized gold nanoparticle composite film and ultrasensitive detection of quercetin.Based on the characteristics of graphene quantum dots and?-CD,the AuNPs-?-CD with layered crochet structure was first prepared by using fully fluorenyl?-cyclodextrin functionalized gold nanoparticles,and electrostatically combined with protonated aminated graphene quantum dots?NH₂-GQDs?to obtain nanocomposites with better electrical conductivity,catalytic and dispersion properties.Then,it is electrodeposited by a cyclic voltammetry method onto a glassy carbon electrode?GCE?to form a stable film.For the detection of quercetin,the linear response range is 0.001-0.2?M and the detection limit is 285 pM.At the same time,flavonoids with similar structures hardly interfere with the determination of QR.In addition,the sensor has been applied to the detection of quercetin in honey,tea,honeysuckle and human serum with satisfactory results.3.Study on the recognition of tryptophan enantiomers based on Cu2-?-CD/aminated graphene quantum dot ordered electrochemical chiral interface.For the first time,a novel simple ordered electrochemical chiral sensor was prepared by electrodeposition method using ordered assembly of NH₂-GQDs and Cu₂-?-CD.It was used for chiral recognition of tryptophan molecules and explored the effect of pH and temperature on its performance.Under the same conditions,the analytical studies have shown that the chiral sensor has a higher current response to L-tryptophan?L-Trp?than D-tryptophan?D-Trp?,and the difference of current can be up to 6.4?A to 1 mM tryptophan enantiomer.This method provides potential application value for the early prediction of tryptophan enantiomers.