Quantitative Imaging of Organic Ligand Density on Anisotropic Inorganic Nanocrystals
Quantitative Imaging of Organic Ligand Density on Anisotropic Inorganic Nanocrystals
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DOI：
10.1021/acs.nanolett.9b02434
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发表时间：
2019-09-01
期刊：
影响因子：
10.8
通讯作者：
Huang, Pinshane Y.
中科院分区：
文献类型：
--
作者：
Janicek, Blanka E.;Hinman, Joshua G.;Huang, Pinshane Y.
纳米颗粒表征中的一个长期挑战是了解有机配体在无机纳米颗粒表面的各向异性分布。在这里，我们表明，使用电子能量损失谱在像差校正的扫描透射电子显微镜，我们可以直接可视化和量化金纳米棒（AuNRs）上的配体分布。这些实验分析了石墨烯基底上的数十种颗粒，深入了解了配体结合密度在单个纳米颗粒内部和之间的变化。我们表明，十六烷基三甲基溴化铵（CTAB）的分布上的AuNR是各向异性的，在纳米粒子的两极的配体密度减少了30%。相比之下，（16-巯基十六烷基）三甲基溴化铵（MTAB）的分布更均匀。这些结果与文献报道的在CTAB涂覆的AuNR末端的较高反应性一致。我们的研究结果表明，电子光谱探测分子分布在软硬界面的影响，以及它们如何产生空间异质性的胶体纳米粒子。
A longstanding challenge in nanoparticle characterization is to understand anisotropic distributions of organic ligands at the surface of inorganic nanoparticles. Here, we show that using electron energy loss spectroscopy in an aberration-corrected scanning transmission electron microscope we can directly visualize and quantify ligand distributions on gold nanorods (AuNRs). These experiments analyze dozens of particles on graphene substrates, providing insight into how ligand binding densities vary within and between individual nanoparticles. We demonstrate that the distribution of cetyltrimethylammonium bromide (CTAB) on AuNRs is anisotropic, with a 30% decrease in ligand density at the poles of the nanoparticles. In contrast, the distribution of (16-mercaptohexadecyl)trimethylammonium bromide (MTAB) is more uniform. These results are consistent with literature reported higher reactivity at the ends of CTAB-coated AuNRs. Our results demonstrate the impact of electron spectroscopy to probe molecular distributions at soft-hard interfaces and how they produce spatially heterogeneous properties in colloidal nanoparticles.