Identification Of Tyrosine Chiral Molecules And Adsorption Of Azo Dye By Graphene Hybrid Materials

Chapter 1: It is quite important to recognize chiral amino acids,because they may display prominent difference in the area of biological activities,particularly in biomedical and pharmaceutical analysis.This paper describes a new electrochemical impedance sensor for the discrimination of L-tyrosine（L-Tyr）and D-tyrosine（D-Tyr）using glassy carbon electrode（GCE）modified with gold nanoparticles coated N-Acetyl-L-cysteine（NALC-Au NPs）.By coupling the distinctive properties of Au NPs and NALC,NALC-Au NPs exhibit excellent ability of chiral recognition by significant difference between L-Tyr and D-Tyr on electrochemical impedance spectroscopy（EIS）.UV-vis spectroscopy,fourier transform infrared（FT-IR）spectroscopy,scanning electron microscope（SEM）and EIS were performed to characterize the as prepared NALC-Au NPs and the modified GCE.Moreover,influence factors such as cycles of cyclic voltammetry（CV）for electro-depositing NALC-Au NPs and tyrosine,p H and concentration of tyrosine were investigated with regard to the effect on enantioselective interaction.The discrimination range and detection limit of the proposed sensor were 10-769 μmol·L-1 and 3 μmol·L-1,respectively.Chapter 2: The Au NPs-COOH-CH₃-β-CD-GNs nanocomposite materials was successfully synthesized and modified onto the surface of glassy carbon electrode for the chiral recognition of tyrosine isomer.The material combines the properties of graphene,gold nano-good conductivity and cyclodextrin chiral recognition,the tyrosine corresponding isomers have a good chiral recognition effect.And that,when the concentration of tyrosine was 566 μmol/L,p H =5.0 and modification amount of Au NPs-COOH-CH₃-β-CD-GNs was 6 μL and the incubation time was 5 minutes,Au NPs-COOH-CH₃-β-CD-GNs/GCE sensor for chiral isomers recognition effect was best.The preparation method of the material is simple,the detection range is wide,and it has a broad prospect for the application oftyrosine in medicine.Chapter 3: In textile industry,approximately 15% of overall dyestuff were lost during the dyingprocess and released into environment via wastewater.Some of azo dyes and their degradationproducts are toxic,mutagenic or carcinogenic,which pose a threat to aquatic living organisms andhuman health.However,due to the stability and resistant to aerobic degradation,chemical andphysical processes have to be considered for removing azo dyes from wastewater.This paper describes the synthesis of β-cyclodextrin functionalized graphene nanosheets（β-CD-GNs）and investigation for the removal of dye pollutants.By coupling the distinctive properties of graphene and β-cyclodextrin,β-CD-GNs exhibited excellent adsorptivity for acid scarlet G（ASG）and Orange II in a very short adsorption equilibrium time,<3.0 min.The adsorption mixture was easily removed by centrifugation,that made β-CD-GNs a potentially attractive adsorbent for water purification.The adsorption isotherms were examined by Langmuir and Freundlich models,and the satisfactory fitting to the Langmuir model suggested the adsorption on β-CD-GNs as a mono-layer coverage.