Preparation Of Luminescent Nanomaterials And Their Application In Fluorescence Detection

In recent years,luminescent nanomaterials have potential applications in the fields of biomedicine,solar cells,optoelectronics,and chemical sensing due to their unique fluorescence properties.In this thesis,two different copper nanofluorescent materials and a novel carbon quantum dot were successfully synthesized,and by exploring their surface physicochemical properties and tapping their applications in the field of chemical sensing,it was found that the synthesized fluorescent nanomaterials could rapidly and sensitively detect hexavalent chromium ions and the antibiotic metronidazole in water bodies.This thesis focuses on the synthesis of copper nanofluorescent materials,doped carbon quantum dots and their applications in fluorescence detection.The main works are as follows:（1）New nitrogen-and sulfur-doped carbon quantum dots（N and S-CDs）were successfully synthesized by a one-step hydrothermal method with glucose as the carbon source and DL-homocysteine as the nitrogen and sulfur source.The fluorescence quantum yield of N、S-CDs was 12.32%at the optimum reaction temperature of 220℃,reaction time of 8 h and the concentration of both glucose and DL-homocysteine of 45 mmol/L（the concentration ratio of 1:1）,which was significantly better than that of the undoped N、S-CDs.The synthesized nitrogen and sulfur double-doped new carbon quantum dots can be successfully applied to the detection of Cr（VI）ions,and linearly correlated with the Cr（VI）concentration in the range of 0-10μmol/L with F₀/F=0.0072c+0.9994,R²=0.9985,and the lowest detection limit of Therefore,N and S-CDs can be used as selective detection fluorescent probes for Cr（VI）.（2）A method based on ascorbic acid-protected copper nanoparticles（CuNPs）for the highly selective detection of Cr（VI）in water was constructed.The CuNPs were synthesized easily by the reduction of copper nitrate with ascorbic acid under the conditioning of sodium hydroxide solution using a one-pot synthesis method.The synthesized CuNPs exhibited high and stable fluorescence properties,and due to the internal filtration effect,Cr（VI）could quench the CuNPs fluorescence,so they could be used as highly sensitive Cr（VI）sensors.The fluorescence intensity of CuNPs was linearly correlated with the Cr（VI）concentration in the range of 0-10μmol/L,F₀/F=0.03457c+0.99714,R²=0.9944,and the detection limit was 0.1011μmol/L.The method can detect Cr（VI）rapidly,sensitively and selectively.（3）Copper nanofluorescent materials（CuNPs@PVP）were synthesized using a one-pot synthesis method with copper nitrate as the copper source,glucose as the reducing agent and polyvinylpyrrolidone as the protecting agent.The effects of reaction time,reaction temperature and amount of each reactant on the fluorescence properties of the prepared copper nanomaterials were investigated.The antibiotic metronidazole（MNZ）had a strong quenching effect on the synthesized copper nanomaterials,and the effects of metronidazole concentration,time and environmental p H on the quenching process were explored.Based on this,a fluorescence detection method for MNZ was established,and the MNZ concentration was linearly correlated in the range of 3-10μmol/L with F₀/F=0.00738c+1.03388,R²=0.9962,and the minimum detection limit was 0.169μmol/L.The method can detect metronidazole rapidly,sensitively,and with high selectivity.