Iodide ions control seed-mediated growth of anisotropic gold Nanoparticles

Jill E. Millstone, Wei Wei, Matthew R. Jones, Hyojong Yoo, Chad A. Mirkin

Research output: Contribution to journalArticlepeer-review

338 Scopus citations


There are now a variety of preparatory procedures for nanoscale gold rods, triangular prisms, and spheres. Many of these methods rely on seed-mediated approaches with cetyltrimethylammonium bromide (CTABr) as a surfactant. Interestingly, seemingly similar preparatory procedures yield very different morphologies, and although there have been a variety of proposals regarding the importance of different steps in shape control, there is no self-consistent procedure that allows one to take one batch of spherical seeds and grow either rods, prisms, or larger polyhedra in a controlled manner. In this report, it is shown that CTABr, depending upon supplier, has an iodide contaminant (at a significant but varying level), which acts as a key shape-directing element because it can strongly and selectively bind to the Au (111) facet and favor the formation of anisotropic structures. Furthermore, by starting with pure CTABr and deliberately adjusting iodide concentration, one can reproducibly drive the reaction to predominantly produce one of the three target morphologies.

Original languageEnglish (US)
Pages (from-to)2526-2529
Number of pages4
JournalNano letters
Issue number8
StatePublished - Aug 2008

ASJC Scopus subject areas

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


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