Quantitative Imaging of Organic Ligand Density on Anisotropic Inorganic Nanocrystals

Blanka E. Janicek, Joshua G. Hinman, Jordan J. Hinman, Sang Hyun Bae, Meng Wu, Jacob Turner, Huei Huei Chang, Eugene Park, Rachel Lawless, Kenneth S. Suslick, Catherine J. Murphy, Pinshane Y. Huang

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Pages (from-to)6308-6314
Number of pages7
JournalNano letters
Issue number9
StatePublished - Sep 11 2019


  • cetyltrimethylammonium bromide
  • electron energy loss spectroscopy
  • gold nanorods
  • ligand binding density
  • ligand characterization
  • scanning transmission electron microscopy

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering


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