金纳米粒子表面自组装巯基十一烷醇单分子层体系的制备及其光散射特性研究

采用柠檬酸钠还原法制备了水相金纳米粒子, 通过巯基的自组装, 成功获得了巯基十一烷醇(MUN)单分子层保护的金纳米粒子. 用紫外可见光谱、透射电子显微镜、激光散射粒度分析、同步散射光谱和发射光谱等手段对组装前后的金纳米粒子的性质进行了研究. 结果表明: 制备的金纳米粒子最大吸收波长518 nm, 形状规则, 粒度均匀, 平均粒径为14.6 nm, 每个粒子含有约9.64×10⁴原子; 组装之后的金纳米粒子表面等离子体共振吸收峰红移17.0 nm, 平均粒径增大为20.2 nm, 组装层的平均厚度2.8 nm, 与MUN分子长度相当, 结合量实验证明每一个金纳米粒子可以结合约7.52×10³个MUN, 表面覆盖率为83.6%, 粒子分散均匀, 稳定性增强可长期保存; 同步散射光谱变化和发射光谱中分频、差频和倍频峰的存在证明, 金纳米粒子组装前后均具有非线性光学特性.

Preparation and Light-scattering Characterization of Gold Nanoparticle Self-assembled by Mercaptoundecanol Monolayer

A water-soluble gold nanoparticle was prepared with trisodium citrate and hydrogen tetrachloroaurate by reduction method. Using mercaptoundecanol as a self-assembled molecule, self-assembled monolayer-protected gold nanoparticle was obtained. Various techniques, such as UV-Vis spectrophotometry, transmission electron microscopy, laser scattering size analysis, synchronous light-scattering spectrum, emission spectrum, were used to characterize nanoparticles. The diameter of monolayer-protected gold nanoparticle was about 20.2 nm, bigger than that of gold nanoparticle of 14.6 nm. There were about 9.65×10⁴ gold atoms in a gold nanoparticle and 7.52×10³ mercaptoundecanol molecules binding to it. The monolayer-protected gold nanoparticle was global and compact. Compared with gold nanoparticle (518 nm), its UV-Vis absorption peak has been red-shifted to 535 nm. Both gold nanoparticles and monolayer- protected gold nanoparticles had a nonlinear light-scattering characteristic.