title: A Fast and Efficient Replacement of CTAB with MUA on the Surface of Gold Nanorods Assisted by a Water-Immiscible Ionic Liquid.
abstract: 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][Tf2N]. That is, by mixing IL, mercaptoundecanoic acid (MUA)/IL (200 × 10-3m) 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.
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing, 100048, P. R. China.
authors.forename: Linjia
authors.initials: L
authors.lastname: Su
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing, 100048, P. R. China.
authors.forename: Song
authors.initials: S
authors.lastname: Hu
authors.affiliation: 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.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, 100084, P. R. China.
authors.forename: Zhuoran
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, 100084, P. R. China.
authors.forename: Weiping
authors.initials: W
authors.lastname: Gao
authors.affiliation: Department of Chemistry, Capital Normal University, Beijing, 100048, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.affiliation: 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.
authors.forename: Minghua
authors.initials: M
authors.lastname: Liu
keywords: cytotoxicity; gold nanorods; ionic liquid; ligand exchange; surface coating