Aqueous Synthesization Of Near-infrared ?-? Group Quantum Dots And Their Application In Analysis

Due to near infrared quantum dots excellent performance,near-infrared fluorescent quantum dots has already made great progress in the field of solar cells,chemical analysis,drug residues detection,photocatalytic and other fields.Aqueous phase method has the advantages of simple operation,good biocompatibility,etc.In this paper,we have established the room temperature aqueous-phase method to synthetize green and harmfulless near infrared water soluble silver chalcogenide quantum dots,and on this basis,mainly explored the quantum dots as fluorescent probes on the analysis of the analytical field?metal ions and antibiotics detection?and biological field in terms of specific application.The main contents were as follows:?1?near-infrared quantum dots such as Ag2 S,Ag₂Se QDs were synthesized by room temperature aqueous phase method.And at the same time we studied the fluorescence properties of Ag2 S,Ag₂Se prepared under different conditions including the molar ratio of raw materials,pH value,the amount and category of surfactant,reaction time and temperature and other factors.And structure of quantum dots,morphology,valence state,were characterized by using X-ray powder diffraction,transmission electron microscopy,uv-vis absorption spectrum and fluorescence spectrum instrument.The results were as follows: the quantum dots with excellent properties can be synthesized when using N-acetyl-L-cysteine as the surface modifier,the pH value is between 4.2 and 4.4,the best material feeding ratios of N-acetyl-L-cysteine/Ag are both of 6/5;the best material ratios are 5/1?Ag/S?,20/3?Ag/Se?.We found the fluorescence intensity of Ag2 S,Ag₂Se quantum dot kept stable within 60 days and the optical intensity of them under continuous xenon light is almost unchanged around 480 minutes.?2?Based on the fluorescence quenching mechanism,as fluorescent probe,Ag2 S,Ag₂Se QDs were used to detect the concentration of Cu2 +,Hg2 +,Ag⁺.The results show that with the increase of metal ion concentration,the optical intensity of Ag₂S?Ag₂Se QDs decline gradually.?3?As a fluorescent probe,Ag2 S,Ag₂Se QDs detected streptomycin sulphate quantitatively found that streptomycin sulphate could enhance Ag2 S,Ag₂Se QDs fluorescence intensity to a certain extent.Relative fluorescence enhancement degree I of Ag2 S QDs and the concentration of streptomycin sulfate between 2.5 x 10^-7 and 17.5 x 10^-7 mol/L showed the good linear relationship after fitting a linear equation: I = 0.009 + 1.032 C,the linear correlation coefficient was R = 0.9971.The minimum limit of Ag2 S QDs detecting streptomycin sulphate was 1.99 x 10^-7 mol/L.Ag2 Se QDs and the concentration of streptomycin sulfate between 5 x 10^-7 and 15 x 10^-7 mol/L showed the good linear relationship after fitting a linear equation: I=0.791+0.064 C,the linear correlation coefficient was R = 0.9979.The minimum limit of Ag2 Se QDs detecting streptomycin sulphate was 2.3 x 10^-7 mol/L.