The Preparation And The Electrochemical Chiral Recognition Of Graphene/Chiral Polymer Composite Electrodes

Graphene as one of the conductive masterials,has rasied wide attention for researchers at home and abroad.In particular,studies on Graphen nanocomposites has become one of the hotspots of their applied investigation.In this paper,we chosed graphene as conductive material,chiral polymer as chiralselector,we prepared graphene/poly(glutamic acid)composites and graphene/chitosan composites and used graphene/chiral polymers composites as electrode materials of electrochemical sensor.The structure interaction of the composites were characterized by X-ray diffraction(XRD),Infrared spectra(IR).The morphology of the products were characterized by transmission electron microscopy(TEM)and scanning electron microscope(SEM).We used the two kinds of graphene nanocomposites as electrochemical electrodes masterials and studied their electrochemical properties by cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS),we also analysed the electrochemical recognition ablity of the graphene/chiral polymer for amino acid enantiomers through differential pulse voltammetry(DPV).We discussed the chirality,chiral recognition,theories and research status in the introduction,we also introduced the classifiy of electrochemical sensor and the recognition theories.Finally,we introduced the research status and application prospects of graphene composites in the filed of electrochemical sensor.(1)In this chapter,we obtained 3D structure maroporous graphene thin films by ice-induced phase separate method,the poly(glutamic acid)stabilized on the surface of graphene was synthesized by electrochemical polymerization method.The graphene/poly(glutamic acid)composites wrer used as electrode material to recognize tryptophan enantiomers by DPV,the results showed that the modified electrodes presented a higher recognition effect to L-tryptophan than D-tryptophan,the recognition efficiency was 1.2.The modified electrodes not only combained the high electrical conductivity of 3D graphene but also increased the hydrophily by poly(glutamic acid).The modified electrodes showed low costing,high recognition efficiency,good repratability and stability.The preparation method of macroporous graphene and poly(glutamic acid)composites is expected to be used for the field of electrochemical sensor.(2)In this chapter,in the first place,homogenized GO/CS dispersion was prepared by using the hydrogen bonding between GO and chitosan(CS);Secondly,in order to improve the conductivity of the composite materials,we reducd GO by ascorbic acid by green and environment-friendly method,we obtained the dispersive RGO/CS solution;finally,the RGO/CS composites film was deposited evenly onto the surface of ITO glass by vacuum extraction,the RGO/CS@ITO electrode was prepared.The electrode morphology and conductivity of graphene chitosan composites with different concentration ratio and thickness were studied.The DPV results showed that RGO/CS@ITO could have a good recognition with high sensitivity for L-Trp enantiomers when the RGO/CS film obtained in the condition of200 μL and the recognition efficiency is 1.2.The preparation method of RGO/CS is easy and low costing.The RGO/CS@ITO showed excellent recognition for L-Trp,this material can be used in the field of sensor.(3)In this chapter we used RGO/CS@ITO as working electrode,chose the phenylalanine enantiomers,methionine enantiomers,proline enantiomers,alanine enantiomers,and glutamic acid enantiomers as the research object.potassium ferricyanide was firstly introduced the in the amino acid solution,the interaction between amino acid enantiomers and RGO/CS@ITO interface led the electrical current signal differences,it reflected the electrochemical recognition abilities of modified electrodes for amino acie enantiomers.The experiment results showed that modified electrodes had a good recognition of D-phenylalanine with higher intensity than L-phenylalanine.In addition,the recognition efficiency of L-Methine,L-proline,L-alanine,L-glutamic acid were higher than that of D-Methine,D-proline,D-alanine and D-glutamic acid.The recognition value is 1.18,1.38,1.16 and 1.24.These data clearly indicated that the addition of redox probes to the test system can increase the identification of enantiomers of amino acids.