Nanomaterials Technology Expands The Study Of The Identification Of Chiral Pollutants In The Environment By Spectroscopy

Chirality is one of the basic attributes of the universe.Although the chiral compounds are the same in their atomic composition,they are mirror images of each other in the stereo structure.Natural organisms in the universe are also diverse in the manifestations of the basic characteristics of rivalry.The amino acids in organisms are basically left-handed,but the presenting state of nucleic acids is opposite to that of amino acids.Therefore,the diversities between chiral enantiomers can not be ignored,and the impacts of some different enantiomers on the human body can be described as quite different.In the environment,there are also chiral pollutants.Some biological effects such as carcinogenicity,gene mutations and teratogenicity may exist in these substances,and these chiral pollutions,if being ingested by organisms that live in the environment for a long time,will affect the organisms.So the research on chiral pollutants in the environment has also attracted the attention of experts and scholars from all fields.Based on this,this thesis took phenylglycine,carnitine,mandelic acid and aspartame as the research objects,and carried out chiral recognition research by fluorescence spectrophotometry and resonance Rayleigh scattering method,gold nanoparticles and semiconductor quantum dot?QDs?as probe reagents.In this paper,the characteristics of fluorescence spectra or resonance Rayleigh scattering spectra of various systems,optimal experimental conditions and selective experiments were carried out,and the analysis of actual samples based on fluorescence spectroscopy and resonance Rayleigh scattering spectroscopy were established.This paper was completed under the support of the National Natural Science Foundation of China?No.21875015;No.21475014?.Its main research contents are as follows:1.Recognition of Chiral Glycerol on Ag⁺functionalized N-Acetyl-L-cysteine-coated CdTe QDsIn this experiment,CdTe QDs?NALC-CdTe QDs?were coated with N-acetyl-L-cysteine as fluorescent probes,and a rapid and simple method for chiral recognition of phenyl glycine was established.The synthesized N-acetyl-L-cysteine-coated CdTe QDs were characterized by transmission electron microscope,Fourier transform infrared spectrometer,X-ray diffraction and fluorescence spectrometer.When N-acetyl-L-cysteine-coated CdTe QDs reacted with R-phenylglycine and S-phenylglycine,the fluorescence intensity increases,but there was no enantiomeric difference.When Ag⁺was present,fluorescent spectra had interesting changes.After reaced with R-phenylglycine and S-phenylglycine,S-phenylglycine enhanced the intensity of the fluorescence spectrum of Ag⁺functionalized and N-acetyl-L-cysteine-coated CdTe QDs,whereas R-phenylglycine decreased the intensity of the fluorescence spectrum.After literature research,it was inferred that the reason for this phenomenon may be the difference in the three-dimensional structure of the molecule.The rotation direction of N-acetyl-L-cysteine-coated CdTe QDs is consistent with that of S-phenylglycine.As a result,the fluorescence spectrum is enhanced,and the fluorescence spectrum of the QDs reacted with R-phenylglycine decreases,also there is a good linear relationship within a certain range of concentrations.After the factors that may affect the experiment,such as the type of buffer solution,pH value and reaction time were optimized,the optimal conditions for the experiment were found,and a simple and rapid method for the detection of phenyl glycine was established.2.Recognition of Chiral Carnitine via Cu²⁺-functionalized N-acetyl-L-cysteine-coated CdTe QDsFor the separation of chiral enantiomers,simultaneous determination without separation has become the focus of scholars from all fields.In this experiment,the carnitine enantiomers were successfully measured using Cu²⁺-functionalized N-acetyl-L-cysteine-encapsulated CdTe QDs?NALC-CdTe QDs?without simultaneous separation,and this method is simple,inexspensive and universal operable.Carrotine enantiomers were chirally identified based on a novel spectroscopic method-resonance Rayleigh scattering?RRS?.The RRS signal of the NALC-CdTe QDs is weak.But when Cu²⁺is added,the RRS signal will increase sharply.After adding carnitine,the RRS signal of NALC-CdTe QDs will be different.D-carnitine will make RRS signal increase,but L-carnitine will reduce the RRS signal,so the determination of the opponent carnitine separation achieved.The experimental conditions were optimized to obtain the optimal conditions.Under this condition,good correlation linearity was obtained,and this method was applied to the actual sample weight loss drug L-carnitine.The results were satisfying.3.Recognition of Mandelic Acid by Graphene Oxide Modified CdTe QDsIn this experiment,when CdTe QDs were synthesized,graphene oxide was successfully used as one of the ligands to modify the surface of CdTe QDs.Based on the resonance Rayleigh scattering method,graphene oxide-modified CdTe QDs?GO-CdTe QDs?were used as scattering probes to establish a simple and convenient spectroscopic method for the detection of mandelic acid.The synthesized graphene oxide-modified CdTe QDs were characterized by transmission electron microscopy,fourier transform infrared spectroscopy and resonance Rayleigh scattering.The results showed that the synthesis of GO-CdTe QDs was ccessful.Because of the unique properties of graphene oxide,D-mandelic acid increases the resonance Rayleigh scattering signal of GO-CdTe QDs after addition of mandelic acid,while L-mandelic acid has no effect on it,so this method can not only detect D-Mandelic acid,also be able of quantitative determination of L-mandelic acid.The conditions required for the experiment were optimized,and the optimal conditions were determined,also the phenomenon was more pronounced.Moreover,the experimental system was analyzed and applied by the standard addition recovery method.It was pleased with the results.4.Recognition of Aspartame by Histidine-Functionalized Gold NanoparticlesThe characteristics of Au nanoparticles,unique surface plasmon resonance optical properties,such as high extinction coefficient and distance-dependent surface plasmon resonance,were used to detect aspartame.Among the amino acid with the chirality,the experiment uses histidine as a ligand,providing a chiral environment for the detected chiral substance and synthesizing chiral D/L-His-Au NPs.When using HEPES buffer solution to control pH=7.6,aspartame can significantly reduce the intensity of Resonance Rayleigh Scattering?RRS?spectra of Au nanoparticles,thus achieving the purpose of detecting Aspartame.Aspartame have the carboxyl group,the keto group,the ester group and the amino group,and is easily reacted with histidine.The amino group of histidine can interact with the carboxyl group of aspartame through electrostatic interaction and hydrogen bonding,so accumulation of D/L-His-Au NPs occurs,resulting in the annihilation of the RRS spectra.The concentration range of this experiment is 10^-5-10^-7 mol/L,correlation coefficient R²=0.99841,LOD=0.08?mol/L.Moreover,the experimental system was analyzed and applied using the standard addition recovery method.The results were satisfying.