Construction Of Peptide And Fluorescent Carbon Nanomaterial Probes And Their Applicationsin Analytical Detection

In this paper,peptide fluorescent materials,carbon materials and fluorescent carbon/gold composite materials,combined with fluorescence spectroscopy and colorimetry,are used to construct sensors for detecting Cu²⁺,Cr₂O₇^2-in actual water samples and L-ascorbic acid（VC）in beverage samples.The main contents of this thesis are as follows:Chapter 1:This chapter mainly introduces peptide fluorescent materials,carbon materials and fluorescent carbon/gold composite materials,and systematically explains the research background,physical and chemical properties,and common preparation methods of peptide fluorescent materials,carbon nanomaterials,and fluorescent carbon/gold composite materials.And its application in analysis,testing and application research;combining the above-mentioned ideas to put forward the design idea of this paper,and describe the research background and current situation of several testing objects;prospect the application prospects of nanomaterials in other fields.Chapter 2:Based on the fluorescence quenching effect of copper ions(Cu²⁺)on rhodamine B-labeled peptides,a fluorescence sensor for copper ion detection was constructed.The polypeptide fluorescent material in this article is one rhodamine B fluorophore labeled with each polypeptide.During the labeling process,the rhodamine B fluorophore bonds with the amino group of the lysine side chain of the polypeptide terminal through the carboxyl group,because Cu²⁺promotes rhodamine B Protected peptide（RBP）fluorescence quenching,using resonance light scattering analysis,ultraviolet-visible absorption spectroscopy,fluorescence lifetime test and circular dichroism spectroscopy to study the sensing mechanism of detecting copper ions,and it is found that the addition of copper ions(Cu²⁺)induces peptides The structure changes to make the Rhodamine B fluorophores close to each other,which leads to aggregation between the copper ions and the polypeptide to induce fluorescence quenching.The linear range of the sensor for detecting copper ions is5×10-4-1×10-2μmol/L and 0.1-7μmol/L,the detection limit is 0.29 nmol/L,and it has good selectivity.Applied to the detection of Cu²⁺in lake water.Chapter 3:Based on the static quenching effect of dichromate ion(Cr₂O₇^2-)on sulfur and nitrogen-doped carbon nanosheets（TCNs）,a highly sensitive and selective analysis method for the detection of dichromate ion(Cr₂O₇^2-)was established.The carbon nanomaterials in this article are carbon nanosheets containing sulfur and nitrogen（TCNs）synthesized by the one-pot method of 6-mercaptopurine,sodium citrate,N,N-dimethylformamide.The addition of Cr₂O₇^2-promotes sulfur and nitrogen Fluorescence quenching of carbon nanosheets（TCNs）,using ultraviolet-visible absorption spectroscopy,fluorescence lifetime test and X-ray photoelectron spectroscopy,as well as the fluorescence quenching of Cr₂O₇^2-on TCNs at different temperatures,the sensing mechanism of detecting Cr₂O₇^2-was studied.Chromate ion(Cr₂O₇^2-)is added to statically quench the fluorescence of sulfur and nitrogen doped carbon nanosheets（TCNs）.The main reason is that chromate ion(Cr₂O₇^2-)undergoes redox reaction with sulfur and nitrogen doped carbon nanosheets（TCNs）,which causes static quenching.The linear range of the sensor is 0.5～140μmol/L,and the detection limit（S/N=3）is 0.038μmol/L.In addition,the sensor has good selectivity for the detection of Cr₂O₇^2-,and can be used for the detection of Cr₂O₇^2-in lake water samples.Finally,it was applied to the detection of Cr₂O₇^2-in lake water.Based on the static quenching effect of dichromate ion(Cr₂O₇^2-)on sulfur and nitrogen-doped carbon nanosheets（TCNs）,a highly sensitive and selective analysis method for the detection of dichromate ion(Cr₂O₇^2-)was established.The carbon nanomaterials in this article are carbon nanosheets containing sulfur and nitrogen（TCNs）synthesized by the one-pot method of6-mercaptopurine,sodium citrate,N,N-dimethylformamide.The addition of Cr₂O₇^2-promotes sulfur and nitrogen Fluorescence quenching of carbon nanosheets（TCNs）,using ultraviolet-visible absorption spectroscopy,fluorescence lifetime test and X-ray photoelectron spectroscopy,as well as the fluorescence quenching of Cr₂O₇^2-on TCNs at different temperatures,the sensing mechanism of detecting Cr₂O₇^2-was studied.Chromate ion(Cr₂O₇^2-)is added to statically quench the fluorescence of sulfur and nitrogen doped carbon nanosheets（TCNs）.The main reason is that chromate ion(Cr₂O₇^2-)undergoes redox reaction with sulfur and nitrogen doped carbon nanosheets（TCNs）,which causes static quenching.The linear range of the sensor is 0.5～140μmol/L,and the detection limit（S/N=3）is 0.2μmol/L.In addition,the sensor has good selectivity for the detection of Cr₂O₇^2-,and can be used for the detection of Cr₂O₇^2-in lake water samples.Finally,it was applied to the detection of Cr₂O₇^2-in lake water.Chapter 4:Fluorescent carbon materials were prepared by one-pot method with sodium citrate,thioacetamide,N,N-dimethylformamide,and composite materials were synthesized with gold ions and found that the fluorescent carbon The gold composite material has oxidase activity,which can catalyze the oxidation of3,3’,5,5’-tetramethylbenzidine into a blue product,and the addition of L-ascorbic acid inhibits the oxidase activity of the fluorescent carbon/gold composite material,based on this Based on this principle,a colorimetric sensor of L-ascorbic acid（VC）is constructed.The linear range of the sensor for detecting L-ascorbic acid is 1-20μmol/L,and the detection limit is 0.6μmol/L.This method has the advantages of simple operation,high sensitivity,and low cost.It can be used for the detection of VC in beverage samples.