Surface-enhanced Raman spectroscopy of polyelectrolyte-wrapped gold nanoparticles in colloidal suspension

Sean T. Sivapalan, Brent M. Devetter, Timothy K. Yang, Matthew V. Schulmerich, Rohit Bhargava, Catherine J. Murphy

Research output: Contribution to journalArticle

Abstract

The rapidly expanding field of surface-enhanced Raman spectroscopy (SERS) has helped fuel an intense interest in noble metal nanoparticle synthesis. An in-suspension approach for quantifying SERS enhancement and relating that enhancement to a spontaneous Raman equivalent signal is described. Gold nanoparticles of various shapes were wrapped with polyelectrolyte multilayers that trapped Raman reporter molecules at defined distances from the metal core. Electrospray ionization liquid chromatography mass spectrometry (ESI-LC-MS) on digested samples was employed to measure the average number of bound Raman reporter molecules per gold nanoparticle, and inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the average number of gold atoms per nanoparticle. Using these data, SERS signal intensity was compared to a spontaneous Raman calibration curve to compute a spontaneous Raman equivalent factor. Three different geometries of gold nanoparticles (cubes, spheres, and trisoctahedra) were synthesized to investigate edge and corner effects using these quantitative techniques. Finite element method electromagnetic simulations examined the relationship between the different geometries and the observed SERS signal intensities. The experimental observations and theoretical results indicate that cubic gold nanoparticles have the highest effective signal.

Original languageEnglish (US)
Pages (from-to)10677-10682
Number of pages6
JournalJournal of Physical Chemistry C
Volume117
Issue number20
DOIs
StatePublished - May 23 2013

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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