摘要贵金属纳米材料在催化、抗菌、光学领域、生物材料等方面已被广泛应用，是一 种新型功能材料。制备贵金属纳米粒子的方法有很多种，本文采用光化学还原法和液 相化学还原法制备银纳米粒子，并对制备的银纳米粒子进行圆二色谱(CD)和紫外-可 见吸收光谱(UV- vis)表征。考察了脱氧胆酸钠浓度、光照时间、还原剂加入量、手性 分子的浓度等对制备的银纳米粒子 CD 光谱的影响。对制备的银纳米粒子进行离心以 及加入氯化钠，促进银纳米粒子的聚集，考察了对银纳米粒子手性性能的影响。82614

以脱氧胆酸钠作为稳定剂和手性诱导剂，以紫外灯为光源照射硝酸银和脱氧胆酸 钠的混合溶液制备了 NaDC 包覆的银纳米粒子。当脱氧胆酸钠的浓度比较低时，光化 学反应速率比较慢，制备的粒子的 SPR 吸收峰位于 450 nm 左右，半峰宽较宽，表明 粒子的尺寸较大，且尺寸分布较宽。圆二色谱结果表明光化学还原制备的银纳米粒子 具有光学活性，当 NaDC 的浓度为 3 mM 时制备的银纳米粒子的手性信号最强。

采用液相化学还原法，用新配制的 NaBH4 和柠檬酸钠混合溶液还原硝酸银制备 银纳米粒子，通过配体交换反应，制备手性分子组氨酸和脱氧胆酸钠修饰剂的银纳米

粒子。实验结果表明加入手性分子后，经过离心处理的样品在银纳米粒子的表面等离 子体共振(SPR)区域出现手性信号。手性分子的浓度会影响 CD 信号的强弱。组氨酸 浓度为 25 μM 时，制备的银纳米粒子在 390 nm 出现一个正的科顿效应峰，在 450 nm 出现一个负的科顿效应峰。NaDC 的浓度为 120 μM 时制备的银纳米溶胶的手性信号 较强，在 400 nm 左右出现一个负科顿效应峰。

毕业论文关键词：银纳米粒子；手性诱导；光化学还原；液相化学还原

Abstract Noble metal nanomaterial as a kind of new functional material has been widely used in the field of catalysis, antibacterial, optical, biological materials。 There are many kinds of preparation methods for metal nanoparticles。 In this article silver nanoparticles were prepared by photochemical reduction method and liquid-phase chemical reduction method。 The prepared silver nanoparticles are characterized by CD and UV-vis spectra。 The effects of concentration of NaDC, the irradiation time, the amounts of reducing agent and the concentration of chiral molecules on the CD spectra of Ag nanoparticles were investigated。 Adding NaCl solution and centrifugation treatment caused Ag nanoparticles to aggregate, which  have  effect  on the  chirality  of silver  nanoparticles。

NaDC capped Ag nanoparticles were prepared by illumination the mixed solution of silver nitrate and sodium deoxycholate under ultraviolet light with NaDC as the reducing agent and stabilizer。 The photochemical reduction rate is slow when the concentration of NaDC is low。 The SPR absorption band of obtained Ag nanoparticles locates at around 450 nm with broad half band width, indicating that the sizes of the nanoparticles are larger and the size distribution is wider。 The results of CD spectra show that Ag  nanoparticles prepared by photochemical reduction method exhibit chiral properties。 The intensity of the CD signal  is  strongest  when  the concentration  of NaDC is 3  mM。

Using liquid phase chemical reduction method, silver nanoparticles were prepared by the reduction of AgNO3 with fresh prepared solution of NaBH4 and sodium citrate。 NaDC modified and histidine modified Ag Nanoparticles were fabricated by ligand exchange reaction。 The results of the experiment show that Ag nanoparticles with centrifugation treatment exhibit chiral signals in the region of surface plasmon resonance after chiral molecules were added to the nanoparticles。 The concentrations of chiral molecules have influence on the intensity of signals of the CD spectra。 Ag nanoparticles with histidine of 25 μM exhibit a positive Cotton Effect at around 390 nm and a negative Cotton Effect at around 450 nm。 Ag nanoparticles with NaDC of 120 μM have stronger chiral signal, which show a negative   Cotton Effect  at around  400 nm。