Department of Chemistry, University of Miami, 1301 Memorial Drive, Coral Gables, Florida 33146, USA.
ACS Appl Mater Interfaces. 2013 Aug 28;5(16):7906-14. doi: 10.1021/am401997q. Epub 2013 Aug 6.
Au nanomaterials are well-known for their optical properties, where Au nanorods have demonstrated unique capabilities because of their readily tunable size and shape. Unfortunately, functionalization of the material surface is challenging because of their lack of stability after only a few purification cycles. Here, we demonstrate that enhanced Au-nanorod stability can be achieved by purifying the materials using dilute cetyltrimethylammonium bromide (CTAB) wash solutions. To this end, purifying the materials in such a manner shifts the passivant on/off equilibrium to maintain surfactant adsorption to the metal surface, leading to enhanced stability. Interestingly, from this study, a bimodal distribution of Au nanorods was evident, where one species was prone to bulk aggregation, whereas the second population remained stable in solution. This likely arose from defects within the CTAB bilayer at the nanorod surface, resulting in selective material aggregation. For this, those structures with high numbers of defects aggregated, whereas nanorods with a more pristine bilayer remained stable. Coating of the Au nanorods using polyelectrolytes was also explored for enhanced stability, where the composition of the anionic polymer played an important role in controlling materials stability. Taken together, these results demonstrate that the stability of Au nanorods can be directly tuned by the solvent-exposed surface structure, which could be manipulated to allow for the extensive material functionalization that is required for the generation of nanoplatforms with multiple applications.
金纳米材料以其光学特性而闻名，其中金纳米棒由于其尺寸和形状易于调节而具有独特的性能。然而，由于其在经过几次纯化循环后缺乏稳定性，因此对材料表面进行功能化具有挑战性。在这里，我们证明通过使用稀十六烷基三甲基溴化铵（CTAB）洗涤溶液来纯化材料，可以实现增强的金纳米棒稳定性。为此，以这种方式纯化材料会将钝化剂的开/关平衡移动，以保持表面活性剂吸附到金属表面，从而提高稳定性。有趣的是，从这项研究中可以看出，金纳米棒存在双峰分布，其中一种物质容易发生体相聚集，而第二种物质在溶液中保持稳定。这可能是由于 CTAB 双层在纳米棒表面存在缺陷，导致选择性材料聚集。对于这种情况，具有高缺陷数的结构会聚集，而具有更原始双层的纳米棒则保持稳定。还探索了使用聚电解质对金纳米棒进行涂层以提高稳定性，其中阴离子聚合物的组成在控制材料稳定性方面起着重要作用。总之，这些结果表明，金纳米棒的稳定性可以通过暴露于溶剂的表面结构直接调节，这可以加以控制，以允许进行广泛的材料功能化，从而生成具有多种应用的纳米平台。
