手性纳米银粒子的制备及等离子体旋光响应

发布时间：2018-05-09 12:47

本文选题：银纳米粒子 + 光化学还原　；参考：《江苏科技大学》2017年硕士论文

【摘要】：近年来手性银纳米材料由于在手性催化、手性识别、光学领域等方面的应用而受到广泛的关注。本文选用不同的手性小分子作为手性诱导剂和修饰剂,采用光化学还原和液相化学还原法制备出具有手性的银纳米粒子,对制备的银纳米粒子进行紫外-可见吸收光谱(UV-vis)、圆二色谱(CD)、透射电镜(TEM)的表征,并对银纳米粒子手性形成机理进行了初步探讨。采用光化学还原法,在硝酸银和脱氧胆酸钠的混合溶液的pH=10条件下,以AgNO_3溶液为前驱体,脱氧胆酸钠为手性诱导剂和稳定剂,以紫外灯为光源,还原银离子制备了脱氧胆酸钠包覆的银纳米粒子。当脱氧胆酸钠/Ag+摩尔比为6:1时,制备出的银纳米粒子手性信号最强。当脱氧胆酸钠/Ag+摩尔比低时,还原反应速率比较慢,生成的银纳米粒子的表面等离子共振吸收峰位于455 nm左右,半峰宽较宽,粒子的尺寸较大,且尺寸分布较宽。随着摩尔比增大,还原反应速率比较快,在体系中生成的银纳米粒子尺寸分布均匀,粒子的尺寸较小,半峰宽变窄。采用液相化学还原法,以AgNO_3溶液为前驱体,柠檬酸钠与NaBH4的混合溶液为还原剂,还原银离子制备了黄绿色的银纳米溶胶,通过配体交换反应,制备脱氧胆酸钠修饰的银纳米粒子。随着脱氧胆酸钠的浓度增大,银纳米溶胶的SPR吸收峰的强度逐渐增大,半峰宽逐渐减小,银纳米溶胶的SPR吸收峰的最大吸收峰峰位置出现蓝移现象。向银纳米溶胶中加入NaCl能促进纳米粒子的聚集。随着氯化钠的加入量增多,银纳米粒子在400 nm左右的SPR吸收峰的峰强逐渐减弱,SPR吸收峰的最大吸收峰的位置发生红移,银纳米粒子的半峰宽逐渐变窄,并且在600 nm左右出现新的SPR吸收峰。向银纳米溶胶中加入适量的HCl溶液能够促进纳米粒子的聚集,并且增强银纳米粒子的手性信号。采用液相化学还原法,以AgNO_3溶液为前驱体,柠檬酸钠与NaBH4的混合溶液为还原剂,还原银离子制备了黄绿色的银纳米溶胶,通过配体交换反应,制备L-组氨酸修饰的银纳米粒子。L-组氨酸是一种以内盐的形式存在的氨基酸,质子化的氨基和羧基之间存在静电相互作用,会诱导组氨酸修饰的银纳米粒子聚集。当L-组氨酸的浓度比较低,银纳米粒子的聚集程度较低,粒子有序聚集,引起局域电磁场增强,从而使CD信号增强。当L-组氨酸的浓度继续增大时,会引起粒子聚集程度增强,导致粒子无序聚集,使粒子的CD信号减弱。向银纳米溶胶中加入适量的NaCl时能促进纳米粒子的聚集,从而增强银纳米粒子的CD信号。
[Abstract]:In recent years, chiral silver nanomaterials have attracted wide attention due to their applications in chiral catalysis, chiral recognition and optics. In this paper, chiral silver nanoparticles were prepared by photochemical reduction and liquid chemical reduction with different chiral molecules as chiral inducers and modifiers. The silver nanoparticles were characterized by UV-Vis absorption spectra, circular dichroism (CD), transmission electron microscopy (TEM), and the mechanism of chiral formation of silver nanoparticles was discussed. Under the condition of pH=10 of mixed solution of silver nitrate and sodium deoxycholate, AgNO_3 solution was used as precursor, sodium deoxycholate as chiral inducer and stabilizer, ultraviolet lamp as light source. Silver nanoparticles coated with sodium deoxycholate were prepared by reducing silver ions. When the molar ratio of deoxycholate to silver is 6:1, the chiral signal of silver nanoparticles is strongest. When the molar ratio of deoxycholate to Ag is low, the reduction rate is relatively slow. The surface plasmon resonance absorption peak of the silver nanoparticles is about 455nm, the width of the half-peak is wider, the size of the particles is larger and the size distribution is wider. With the increase of molar ratio, the reduction reaction rate is faster, the size distribution of silver nanoparticles in the system is uniform, the particle size is smaller, and the width of the half peak becomes narrower. The yellowish green silver nanosol was prepared by liquid-phase chemical reduction using AgNO_3 solution as precursor and the mixed solution of sodium citrate and NaBH4 as reducing agent. Silver nanoparticles modified with sodium deoxycholate were prepared. With the increase of the concentration of sodium deoxycholate, the intensity of the SPR absorption peak and the half width of the silver nano-sol gradually increased, and the blue shift phenomenon appeared in the position of the largest absorption peak of the SPR absorption peak of the silver nano-sol. Adding NaCl to silver nanoparticles can promote the aggregation of nanoparticles. With the addition of sodium chloride, the peak intensity of the SPR absorption peak of silver nanoparticles at about 400nm gradually weakened and the position of the maximum absorption peak of the SPR absorption peak shifted red, and the half peak width of silver nanoparticles gradually narrowed. A new SPR absorption peak appeared at about 600nm. Adding appropriate amount of HCl solution to silver nanoparticles can promote the aggregation of nanoparticles and enhance the chiral signals of silver nanoparticles. The yellowish green silver nanosol was prepared by liquid-phase chemical reduction using AgNO_3 solution as precursor and the mixed solution of sodium citrate and NaBH4 as reducing agent. L- histidine modified silver nanoparticles. L- histidine is an amino acid in the form of salt. There is electrostatic interaction between protonated amino groups and carboxyl groups, which induces the aggregation of silver nanoparticles modified by histidine. When the concentration of L- histidine is low, the aggregation degree of silver nanoparticles is lower, and the ordered aggregation of silver nanoparticles leads to the enhancement of local electromagnetic field and the enhancement of CD signal. When the concentration of L- histidine continues to increase, the particle aggregation will be enhanced, resulting in the disordered aggregation of particles, and the CD signal of particles will be weakened. Adding appropriate amount of NaCl to silver nanoparticles can promote the aggregation of silver nanoparticles and enhance the CD signal of silver nanoparticles.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;TQ131.22

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