Tuning and maximizing the single-molecule surface-enhanced Raman scattering from DNA-tethered nanodumbbells

Jung Hoon Lee, Jwa Min Nam, Ki Seok Jeon, Dong Kwon Lim, Hyoki Kim, Sunghoon Kwon, Haemi Lee, Yung Doug Suh

Research output: Contribution to journalArticlepeer-review

109 Citations (Scopus)

Abstract

We extensively study the relationships between single-molecule surface-enhanced Raman scattering (SMSERS) intensity, enhancement factor (EF) distribution over many particles, interparticle distance, particle size/shape/composition and excitation laser wavelength using the single-particle AFM-correlated Raman measurement method and theoretical calculations. Two different single-DNA-tethered Au-Ag core-shell nanodumbbell (GSND) designs with an engineerable nanogap were used in this study: the GSND-I with various interparticle nanogaps from ∼4.8 nm to <1 nm or with no gap and the GSND-II with the fixed interparticle gap size and varying particle size from a 23-30 nm pair to a 50-60 nm pair. From the GSND-I, we learned that synthesizing a <1 nm gap is a key to obtain strong SMSERS signals with a narrow EF value distribution. Importantly, in the case of the GSND-I with <1 nm interparticle gap, an EF value of as high as 5.9 ×1013 (average value = 1.8 ×1013) was obtained and the EF values of analyzed particles were narrowly distributed between 1.9 ×1012 and 5.9 ×1013. In the case of the GSND-II probes, a combination of >50 nm Au cores and 514.5 nm laser wavelength that matches well with Ag shell generated stronger SMSERS signals with a more narrow EF distribution than <50 nm Au cores with 514.5 nm laser or the GSND-II structures with 632.8 nm laser. Our results show the usefulness and flexibility of these GSND structures in studying and obtaining SMSERS structures with a narrow distribution of high EF values and that the GSNDs with < 1 nm are promising SERS probes with highly sensitive and quantitative detection capability when optimally designed.

Original languageEnglish
Pages (from-to)9574-9584
Number of pages11
JournalACS nano
Volume6
Issue number11
DOIs
Publication statusPublished - 2012 Nov 27
Externally publishedYes

Keywords

  • core shell particle
  • enhancement factor
  • nanogap
  • plasmonic probe
  • single-molecule detection
  • surface-enhanced Raman scattering

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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