| Chirality is fundamental property of nature and organisms. Many of the reactions in organisms are involved in chiral recognition. The different configurations of the enantiomers can exhibit striking differences in terms of pharmacological activity, metabolic processes, metabolic rate, even in vivo toxicological effect. Therefore, chiral recognition has become a research issue in biological, medical research and pharmaceutical industry. In the field of analytical chemistry, the foreword direction and hotspot for chiral recognition research focus on development rapid, accurate and sensitive methods. While electrochemical method has also received increasing attention with the advantages of low cost, high sensitivity and simplicity. The novel chiral nanocomposite modified electrodes were employed to fabricate chiral surface, and the interaction between the chiral surface and amino acid and its derivatives were primarily investigated by electrochemical method. The main research works are included as follows:1. A fast electrochemical sensing to recognize3,4-dihydroxyphenylalanine (DOPA) enantiomers was proposed based on poly-lysine enantiomers films as matrixes, which were electrodeposited on the surface of glass carbon electrodes via cyclic voltammetry (CV). Differential pulse voltammetry (DPV) and CV were employed to investigate the stereospecific recognition of DOPA enantiomers. The concentration of L-lysine. electro-polymerization cycles. pH and the effect of the temperature on the chiral discrimination were investigated to obtain optimization of the experimental parameters, and the Gibbs’free energy (ΔG) was also discussed. The results showed that not only DOPA enantiomers could be recognized by poly-lysine matrix with the tendency of heterochiral interaction between poly-lysine and DOPA enantiomers. but also the largest discrimination were resided in poly-L-lysine matrix (PLL). The detection limit was0.17μM (S/N=3). and the detection time only spent75seconds. The simple method with rapid recognition, good sensitivity and high stability provide a new perspective to recognize and determine DOPA enantiomers with fast, stabile, selective characteristics.2. A simple and reliable chiral sensing platform for enantioselective recognition of lysine (Lys) enantiomers based on nanostructured semiconductor material (NSM) via electrochemical impedance spectroscopy (EIS) technique was described. The stepwise synthesis process of the NSM was characterized by EIS, scanning electron microscopy (SEM). and X-ray photoelectron spectroscopy (XPS). The enantioselective interaction assay between NSM modified glassy carbon electrode and lysine enantiomers relied on EIS. As a prototype example, good recognition were obtained from the difference of electron transfer resistance (ARet). and the larger ARet can be obtained from D-Lys, linear responses in ARet were found for Lys enantiomers ranging from100nM to10mM with a detection limit of33nM (S/N=3). The developed sensor with the advantages of simple preparation, long-term stability, good sensitivity and commendable selectivity. holds great potential application of the nanostructured semiconductor material in chiral bio-electroanalvsis.3. A simple, sensitive and high selectivity biosensor for the determination of D-amino acid incorporating D-amino acid oxidase (DAAO) immobilized on3,4.9.10-perylene tetracarboxylic acid (PTCA) functionalized carbon nanotubes (PTCA/MWCNTs) nanocomposite modified glass carbon electrode was therefore developed. PTCA acted as a mediator and D-amino acid oxidase immobilization matrix. The advantages of PTCA/MWCNTs nanocomposite were more favorable for enormouse D-amino acid oxidase immobilization and signal amplification. The proposed biosensor elicited responses among a variety of D-amino acid, and the biggest signal was obtained from D-ala. The lower limit of detection is at least10-8and a linear range is10nM to1.5mM. We describe a highly sensitive strategy for specific recognition of D-Ala with high selectivity. |
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