Preparation Of Four Red Fluorescent Carbon Dots And Their Application In Drug Analysis

In this study,four kinds of red fluorescent carbon dots were prepared by microwave method with p-phenylenediamine and hydrochloric acid,ammonium chloride,ammonium oxalate and potassium hydrogen phthalate as raw materials,and then four kinds of red fluorescent carbon dots were applied to the detection of cefradine,nystatin,berberine hydrochloride and cytochrome C,respectively.Good results have been obtained for the detection of related substances in actual samples and mixed samples.The specific research contents are as follows:（1）The red fluorescent carbon dots were prepared by microwave method with p-phenylenediamine and hydrochloric acid as raw materials.The carbon dots were characterized by Fourier transform infrared spectrometer and transmission electron microscope.The results show that the particle size of the prepared red fluorescent carbon dots is about 3.5-4.5 nm,and the surface contains hydrophilic functional groups such as-NH₂,-COOH and-OH.When cefradine concentration was in the range of 2.0×10^-7-8.0×10^-5 mol/L,the fluorescence intensity of carbon point system（ΔI_F）showed a good linear correlation with cefradine concentration,and the detection limit was 8.4×10^-8 mol/L.Secondly,the mechanism of cefradine quenching the fluorescence of carbon point system was investigated.The results showed that the quenching mechanism mainly belonged to internal filtration effect.（2）Using p-phenylenediamine and ammonium chloride as raw materials,the red fluorescent carbon dots were prepared by microwave method,and the carbon dots were characterized by transmission electron microscopy.Characterization results showed that the particle size of the prepared red fluorescent carbon dots was about 3.3-3.8 nm.In the range of1.0×10^-8-1.0×10^-5 mol/L,ΔI_F of carbon point system showed a good linear correlation with nystatin concentration,and the detection limit was 2.7×10^-9 mol/L.When nystatin was added to the carbon point system,the fusion particle size of some carbon points became larger,leading to the fluorescence quenching of the system.The quenching mechanism was explored to be a synergistic effect of internal filtration effect and dynamic quenching.（3）Using p-phenylenediamine and ammonium oxalate as raw materials,red fluorescent carbon dots were prepared by microwave method.Transmission electron microscopy,fluorescence spectrometer and other characterization results showed that when the excitation peak of carbon dots was about 293 nm,the emission peak could reach 699 nm,and the particle size of carbon dots was about 4.5-5.8 nm.Using rhodamine B as a reference,the quantum yield of carbon spot was 17.72%.The concentration of berberine hydrochloride was in the range of 3.0×10^-9-1.0×10^-5 mol/L,and theΔI_F of carbon point system showed a good linear correlation with the concentration of berberine hydrochloride,and the detection limit was 2.6×10^-9 mol/L.（4）Red fluorescent carbon dots were prepared by microwave method with p-phenylenediamine and potassium hydrogen phthalate as raw materials.The prepared carbon dots were characterized,and the results showed that the particle size of the prepared red fluorescent carbon dots was about 1.5-2.5 nm.The concentration of cytochrome C in the range of 2.0×10^-9-1.0×10^-5 mol/L showed a good linear correlation withΔI_F,and the detection limit was 1.5×10^-9 mol/L.When cytochrome C was added to the carbon point system,the fluorescence quenching of the system was investigated,and the quenching mechanism was a synergistic effect of internal filtration effect and dynamic quenching.