Construction Of The Electrodes Based Oncyclodextrins And Their Chiral Sensing Properties For Tryptophan

As an important amino acid,tryptophan has two chiral isomers with similar structures but huge differences in physiological activity,so the effective analysis of the two chiral isomers has important research significance.Electrochemical sensing has attracted much attention due to its low cost,fast response,real-time monitoring,high sensitivity,and simple operation.In an electrochemical sensing system,the properties of the two-phase interface of the working electrode are the decisive factors for its sensing performance.Therefore,the construction of new electrode materials has become an important research direction in this field.Cyclodextrins exhibit chiral selective bonding to amino acid molecules,which makes them play an important role in the construction of new chiral analytical electrode materials.This project uses cyclodextrin derivatives as the basic unit to construct new electrode materials for the analysis and detection of chiral tryptophan enantiomers.The details are as follows:1.Hexakis（6-deoxy-6-L-Cysteine）-α-cyclodextrin（Cys-α-CD）modifies the three-dimensional macroporous carbon（MPC）to obtain L-cysteine-modified cyclodextrin-Macroporous carbon hybrid（MPC-Cys-α-CD）,MPC-Cys-α-CD is modified on the surface of glassy carbon electrode for detection of chiral tryptophan molecules.First,the MPC-Cys-α-CD composite was synthesized,and the physicochemical characterization and morphology of this electrode material were carried out by means of Fourier transform infrared spectroscopy（IR）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,etc.observe.Then,an electrochemical sensor was prepared by using MPC-Cys-α-CD hybrid composite to modify glassy carbon electrode,and its electrochemical recognition effect on chiral amino acids was further studied.The identification conditions of amino acids were optimized by electrochemical studies,and the electrochemical detection performance of chiral tryptophan was further studied by differential pulse voltammetry（DPV）,so that the detection of chiral tryptophan（Trp）could be carried out.Identification and detection.2.Recognition and detection of chiral tryptophan based on polyglutamic acid（P-L-Glu）chimeric silver nanoparticles modifiedβ-cyclodextrin（Ag NPs-β-CD）electrode material.L-Glu is a basicα-amino acid in the human body with amino and carboxyl groups.In this part,glutamic acid forms a dense polyglutamic acid film on the surface of the glassy carbon electrode by the method of electropolymerization.Further,the electropolymerized working electrode was immersed in the Ag NPs-β-CD dispersion solution to make it self-assemble on the electrode surface.Then,chiral tryptophan was detected by stripping voltammetry.Under the optimized experimental conditions,the modified electrode system has higher sensitivity to L-Trp at 8 ℃.3.Construction of P-L-Cys/HAu Cl₄/BSA nanomaterials and chiral electrochemical detection of tryptophan.L-Cys,as an essential amino acid necessary for human body,can be polymerized on the surface of glassy carbon electrode to have good biocatalysis and biocompatibility.In this part,a layer of poly-L-cysteine（P-L-Cys）was modified on the surface of the glassy carbon electrode by electropolymerization,and then Au NPs were modified by electrodeposition.Finally,a layer of bovine serum was dripped on the surface of the electrode.Protein（BSA）,electrodeposited Au NPs can improve the redox electron efficiency in native BSA,thereby more clearly distinguishing chiral tryptophan.The results show that the P-L-Cys/HAu Cl₄/BSA modified electrode has higher detection sensitivity for D-Trp.