Department of Chemistry, Capital Normal University, Beijing, 100048, P. R. China.
Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface, Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
Small. 2017 Mar;13(11). doi: 10.1002/smll.201602809. Epub 2017 Jan 9.
The synthesis and surface modification of gold nanorods (GNRs) is one of the most important and basic issues in nanoscience. Most of the widely investigated GNRs are coated with a cetyltrimethylammonium bromide(CTAB) bilayer. Here, a highly efficient method is proposed to replace CTAB from the surface of GNRs with a bifunctional 11-mercaptoundecanoic acid in order to decrease the possible toxicity caused by CTAB. This ligand exchange is achieved in a biphasic mixture of an aqueous solution and a water-immiscible ionic liquid (IL), [BMIM][Tf N]. That is, by mixing IL, mercaptoundecanoic acid (MUA)/IL (200 × 10 m) and a concentrated aqueous solution of GNRs together, followed by vortex stirring for 90 s, CTAB-capped GNRs with varying aspect ratios can be turned into corresponding MUA-capped GNRs with the same aspect ratio. Furthermore, the formed MUA-capped GNRs can be obtained in a large quantity and stored as powders for easy use. The MUA-capped GNRs with improved biocompatibility and colloidal stability are well suited for further biological functionalization and potential applications. This IL-assisted ligand exchange can reverse the surface charge, enhance the stability of GNRs, and suppress its cytotoxicity.
金纳米棒（GNRs）的合成和表面修饰是纳米科学中最重要和最基本的问题之一。大多数广泛研究的 GNRs 都被十六烷基三甲基溴化铵（CTAB）双层包覆。在这里，提出了一种高效的方法，用双官能团 11-巯基十一酸（MUA）取代 GNRs 表面的 CTAB，以降低 CTAB 可能带来的毒性。这种配体交换是在水相和不混溶的离子液体（IL）[BMIM][Tf N]的两相混合物中实现的。也就是说，将 IL、MUA/IL（200×10 m）和浓缩的 GNRs 水溶液混合在一起，然后涡旋搅拌 90 s，具有不同纵横比的 CTAB 封端的 GNRs 可以转变成具有相同纵横比的相应 MUA 封端的 GNRs。此外，还可以大量得到形成的 MUA 封端的 GNRs，并将其储存为粉末，以便于使用。具有改善的生物相容性和胶体稳定性的 MUA 封端的 GNRs 非常适合进一步的生物功能化和潜在应用。这种 IL 辅助的配体交换可以反转表面电荷，增强 GNRs 的稳定性，并抑制其细胞毒性。
