Preparation Of Heteroatom-doped Carbon Dots And Its Application In Pharmaceutical Analysis

Carbon dots?CDs?not only have many excellent optical properties,but also have good water solubility,stability,low toxicity and other advantages.At present,it has been successfully used in the fields of photocatalysis,environmental monitoring and pharmaceutical analysis.In this thesis,three different heteroatom-doped carbon dots were prepared by hydrothermal method,and a series of studies on their morphology,structure and optical properties were carried out.Finally,they were successfully applied to the field of pharmaceutical analysis.Chapter 1:The structure,emission mechanism and synthesis of carbon dots are briefly introduced.The optical properties of carbon dots and their application research progress in photocatalysis,environmental monitoring,and pharmaceutical analysis are briefly introduced.Chapter 2:A red fluorescent nitrogen-doped carbon dot?N-CDs?was prepared by solvothermal method using acetonitrile as a solvent and p-phenylenediamine as a carbon source at 200°C for 10 hours.A series of characterization studies on N-CDs were performed by TEM,FTIR,XPS,and fluorescence spectroscopy.Its average particle size is 2.1 nm,the optimal excitation wavelength is 493 nm,and the emission wavelength is 623 nm.Based on the internal filtering effect,the fluorescence of N-CDs can be quenched by VB₁₂.Therefore,a label-free,sensitive and highly selective VB₁₂ determination method was established.Based on this method,the linear range was 2-204?mol/L?R²=0.991?.More importantly,red fluorescent N-CDs have been successfully used for the detection of VB₁₂ in drug and food samples.Chapter 3:Boron,nitrogen and sulfur co-doped fluorescent carbon dots?BNS-CDs?were prepared by simple hydrothermal reaction of 4-carboxy phenylboronic acid and 2,5-diaminobenzenesulfonic acid at 200°C for 8hours.Fe³⁺can quench the fluorescence of BNS-CDs by electron transfer with BNS-CDs.Therefore,a label-free,good selectivity and high sensitivity Fe³⁺determination method has been established with a linear range and a detection limit of 1.5-692?mol/L and 87 nmol/L.Then Fe³⁺in food and medicine was successfully detected with fluorescent probes.Chapter 4:Using sodium fluoborate,citric acid,ethylamine and acetonitrile as raw materials,boron,fluorine,and nitrogen co-doped carbon quantum dots?BFN-CDs?were prepared in one pot using a hydrothermal method.The structure and properties of N-CDs were discussed by various analysis methods.The average particle size of N-CDs was 3.97 nm,and the optimal emission wavelength was 467 nm at the optimal excitation wavelength of 363 nm.The fluorescence quantum yield was 65.9%.It has been found that the fluorescence of BFN-CDs can be specifically quenched by nitroimidazole antibiotics,and the mechanism is the internal filtration effect.The nanoprobe system has good selectivity and sensitivity for the specific recognition and detection of nitrazole antibiotics,and has important significance for the monitoring of residual nitroimidazole in the environment.