手性小分子诱导制备具有光学活性的银纳米粒子

发布时间：2018-05-13 02:02

本文选题：银纳米颗粒 + 液相化学还原　；参考：《江苏科技大学》2015年硕士论文

【摘要】：本文采用液相化学还原法和紫外光照化学还原法制备出手性银纳米粒子,并对银纳米粒子的手性传导路径和形成内在机理初步探讨和分析。用人体必需氨基酸之一的组氨酸作为手性诱导剂和稳定剂,冰水新制NaBH4作为快速还原剂,还原前驱体AgNO3,制备组氨酸包裹的银纳米粒子。对得到的银纳米溶胶用紫外-可见吸收光谱、圆二色光谱、透射电镜等方法对银纳米粒子进行表征。分析了组氨酸与银离子摩尔比、pH值对银纳米粒子稳定性和手性信号的影响。当溶液的pH=11.5,组氨酸/Ag+摩尔比为5:1时,制备得到的银纳米粒子的形貌近似于圆球形,在水溶液中单分散性良好,粒子的平均粒径在10 nm左右。银纳米粒子的圆二色谱信号受溶液D,L-组氨酸/Ag+摩尔比影响较大,随着摩尔比的增大,CD信号强度逐渐增强,并在长波方向出现新的科顿效应(Cotton effect)峰。向制备出的银纳米溶胶中加入氯化钠溶液,促使单分散的银纳米粒子聚集,并讨论了该方法制备的银纳米粒子的稳定性。采用液相化学还原法,以脱氧胆酸钠作为手性诱导剂和保护剂,pH=5.0的脱氧胆酸钠水溶液陈化1d后,用新制的NaBH4还原Ag+制备了脱氧胆酸钠包裹的银纳米粒子。制备的银纳米粒子粒径约为20 nm,被脱氧胆酸钠包裹的银粒子通过超分子作用力聚集并吸附在生成的脱氧胆酸棒状聚集体的表面,形成了一种有机/无机复合结构。聚集在脱氧胆酸表面的银纳米粒子之间发生相互作用,使银纳米粒子的CD信号在其表面等离子体共振(SPR)区域表现为裂分的科顿效应(Cotton effect)峰。溶液的pH值对制备的银纳米粒子的手性信号有明显的影响,随着溶液pH值的降低,制备的银纳米粒子的CD信号强度逐渐增强。采用紫外光照还原法,用胆酸盐脱氧胆酸钠当做纳米粒子的手性诱导剂以及防团聚稳定剂,溶液中的前驱体AgNO3被紫外灯照射后被还原,生成单质银聚集形成银纳米粒子,同时脱氧胆酸钠被氧化。实验结果表明随着溶液pH值的提高,紫外光化学还原反应的速度明显增大。随着光照还原时间的增加,相应的CD光谱信号强度不断变大。
[Abstract]:In this paper, the liquid phase chemical reduction method and ultraviolet light chemical reduction method were used to prepare the silver nanoparticles. The chiral conduction pathway and formation mechanism of silver nanoparticles were preliminarily discussed and analyzed. Using histidine, one of the essential amino acids, as chiral inducer and stabilizer, NaBH4 was prepared by using ice water as rapid reductant to reduce the precursor Agno _ 3 to prepare silver nanoparticles coated with histidine. The silver nanoparticles were characterized by UV-Vis absorption spectra, circular dichroism spectra and transmission electron microscopy. The effects of pH value of the molar ratio of histidine to silver ion on the stability and chiral signal of silver nanoparticles were analyzed. When the pH value of the solution is 11.5 and the molar ratio of histidine / Ag is 5:1, the morphology of the prepared silver nanoparticles is approximately spherical, and the monodispersity is good in aqueous solution, and the average particle size is about 10 nm. The circular dichroism (CD) signal of silver nanoparticles is greatly affected by the molar ratio of DnL- histidine / Ag, and the intensity of CD signal increases gradually with the increase of the molar ratio, and a new cotton effecteffect peak appears in the long wave direction. Sodium chloride solution was added to the silver nanoparticles to promote the aggregation of monodisperse silver nanoparticles. The stability of silver nanoparticles prepared by this method was discussed. Silver nanoparticles coated with sodium deoxycholate were prepared by liquid phase chemical reduction with sodium deoxycholate as chiral inducer and pH 5.0 sodium deoxycholate solution aged for 1 day. The silver nanoparticles prepared were about 20 nm in diameter. The silver particles encapsulated by sodium deoxycholate were assembled by supramolecular force and adsorbed on the surface of deoxycholic acid rod aggregates to form an organic / inorganic composite structure. The interaction between silver nanoparticles aggregating on the surface of deoxycholic acid makes the CD signal of silver nanoparticles present in the surface plasmon resonance (SPR) region of silver nanoparticles as the cotton effecteffect of split fraction. The pH value of the solution has an obvious influence on the chiral signal of the silver nanoparticles prepared. With the decrease of pH value of the solution, the CD signal intensity of the silver nanoparticles prepared increases gradually. Using sodium deoxycholate as chiral inducer of nanoparticles and anti-agglomeration stabilizer, the precursor AgNO3 in solution was reduced by ultraviolet lamp to form silver nanoparticles. At the same time, sodium deoxycholate was oxidized. The experimental results show that the rate of UV photochemical reduction increases with the increase of pH value of the solution. With the increase of light reduction time, the intensity of CD spectrum signal increases continuously.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O614.122

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