| Chirality is the basic properties of the living system. In the nature and organism, many reactions are the process of chiral recognition. The different configuration of enantiomers mostly presents distinctly different effect in pharmacological activity, metabolic process and toxicological effects. Therefore, the chiral recognition has the important theoretical and practical significance. A rapid, accurate and sensitive analytical method for chiral recognition should be created. Electrochemical chiral sensor is a kind of new analytical method, which combines chiral recognition with electrochemical measurement technology, and has many advantages such as high sensitivity, good selectivity and simple operation as well as easy miniaturization and automation, and so on. Nanomaterials with excellent characteristics, such as large specific surface area, strong adsorption, good biocompatibility, and has been widely used for electroanalytical chemistry research. The study on the interaction of nanomaterials and chiral molecules can help understand life process, and has significant meaning to biology, medicine engineering and pathology. In this paper, combining the advantages of chiral selectors and nanomaterials, three kinds of electrochemical sensor has been constructed. The main works are as follow:1. The Electrochemical recognition performance of TEMPO-oxidized cellulose nanocrystals/L-cysteine/Au electrode to chiral amino acids: A fast electrochemical sensing to recognize phenylalanine(Phe), leucine(Leu) and valine(Val) enantiomers was proposed based on 2,2,6,6-tetramethyl piperidine-n-oxide(TEMPO)-oxidized cellulose nanocrystals(TOCNC), which were bond with L-cysteine on the surface of Au electrodes. Differential pulse voltammetry(DPV) and cyclic voltammetry(CV) were employed to investigate the stereospecific recognition of the three pairs amino acids enantiomers. The experimental results show that TOCNC has the electrochemical recognition effect to the three pairs amino acids enantiomers. The current response to L-amino acids was more obvious than D-amino acids, suggesting TOCNC had anisotropy to amino acids enantiomers. Meanwhile, through comparing the results of the analysis of amino acids enantiomers via HPLC with cellulose as chiral stationary phases, chiral recognition mechanism of TOCNC to amino acids enantiomers had been discussed. The modified electrode was used for determination of Phe enantiomers under the optimal conditions, and achieved satisfactory results and high detection limit. The simple method with rapid recognition, good sensitivity and high stability provide a new perspective to recognize and determine amino acids enantiomers with fast, stabile, selective characteristics.2. An electrochemical chiral sensor based on the composits of graphene quantum dots and ?-cyclodextrin for discrimination and determination of tyrosine enantiomers: In present study, a sensitive electrochemical sensor based on the composits of graphene quantum dots(GQDs) and ?-cyclodextrin(?-CD) functionalized glassy carbon electrode(GCE) was developed for determination and recognition of tyrosine(Tyr) enantiomers. The prepared nanomaterials were characterized by using transmission electron microscope(TEM) and Fourier transform infrared(FTIR). The modified electrode was constructed by electrodeposition in the solution of mass ratio of ?-CD: GQDs = 10:1. The electrochemical sensor was utilized for detection the single enantiomer of Tyr and the mixture of two enantiomers by cyclic voltammetry(CV), and found that Tyr enantiomers can be effectively recognized. The oxidation peak current ratio of L to D-Tyr reached 2.35, which is attributed to the stereoselectivity of ?-CD to the enantiomeric pair of Try. The linearity ranges of L-Tyr were 0.2 to 1.5 m M and 6 ?M to 100 ?M with the detection limit of 6.07 × 10-9M, and the linearity range and the detection limit of D-Tyr were obtained as 0.1 to 1 m M and 1.03 × 10-7M. The proposed sensor was successfully applied to blood serum samples. In addition, the stability and reproducibility of the prepared modified electrode were investigated.3. Simultaneous determination of nitroaniline isomers based on the compsites of graphene quantum dots and ?-cyclodextrin modified electrode: A simple, sensitive and high selectivity electrochemical sensor for the determination of nitroaniline isomers, incorporating ?-cyclodextrin(?-CD) immobilized graphene quantum dots(GQDs) to modify glassy carbon electrode(?-CD-GQDs/GCE) was therefore developed. The resultant modified electrode, referred to as ?-CD-GQDs/GCE, was explored for the detection of nitroaniline isomers, and realized electrochemical separation. The electrochemical behaviors of nitroaniline isomers on the modified electrode have been studied by differential pulse voltammetry(DPV), to provide highly sensitive and selective analysisi methods for simultaneous recognation and determination of nitroaniline isomers. Two kinds of real samples were analyzed to prove the applicability of the proposed method to determine nitroaniline isomers. |
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