Schulz F, Friedrich W, Hoppe K, Vossmeyer T, Weller H, Lange H
Institute for Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany.
Nanoscale. 2016 Apr 7;8(13):7296-308. doi: 10.1039/c6nr00607h. Epub 2016 Mar 15.
Standard procedures to coat gold nanorods (AuNR) with poly(ethylene glycol) (PEG)-based ligands are not reliable and high PEG-grafting densities are not achieved. In this work, the ligand exchange of AuNR with PEGMUA, a tailored PEG-ligand bearing a C10 alkylene spacer, is studied. PEGMUA provides AuNR with very high stability against oxidative etching with cyanide. This etching reaction is utilized to study the ligand exchange in detail. Ligand exchange is faster, less ligand consuming and more reproducible with assisting chloroform extraction. Compared to PEG ligands commonly used, PEGMUA provides much higher colloidal and chemical stability. Further analyses based on NMR-, IR- and UV/Vis-spectroscopy reveal that significantly higher PEG-grafting densities, up to ∼3 nm(-2), are obtained with PEGMUA. This demonstrates how the molecular structure of the PEG ligand can be used to dramatically improve the ligand exchange and to synthesize PEGylated AuNR with high chemical and colloidal stability and high PEG grafting densities. Such AuNR are especially interesting for applications in nanomedicine.
用基于聚乙二醇（PEG）的配体包覆金纳米棒（AuNR）的标准程序不可靠，无法实现高PEG接枝密度。在这项工作中，研究了AuNR与PEGMUA（一种带有C10亚烷基间隔基的定制PEG配体）之间的配体交换。PEGMUA使AuNR对氰化物氧化蚀刻具有非常高的稳定性。利用这种蚀刻反应详细研究配体交换。在氯仿辅助萃取的情况下，配体交换更快、配体消耗更少且更具可重复性。与常用的PEG配体相比，PEGMUA具有更高的胶体稳定性和化学稳定性。基于核磁共振、红外和紫外/可见光谱的进一步分析表明，使用PEGMUA可获得高达约3 nm⁻²的显著更高的PEG接枝密度。这证明了PEG配体的分子结构如何可用于显著改善配体交换，并合成具有高化学稳定性、胶体稳定性和高PEG接枝密度的PEG化AuNR。这种AuNR在纳米医学应用中特别有意义。
