Plasmonic Dual-Gap Nanodumbbells for Label-Free On-Particle Raman DNA Assays

Jae Myoung Kim, Jiyeon Kim, Kyungin Choi, Jwa Min Nam

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Metal nanostructures with a tunable plasmonic gap are useful for photonics, surface-enhanced spectroscopy, biosensing, and bioimaging applications. The use of these structures as chemical and biological sensing/imaging probes typically requires an ultra-precise synthesis of the targeted nanostructure in a high yield, with Raman dye-labeling and complex assay components and procedures. Here, a plasmonic nanostructure with tunable dual nanogaps, Au dual-gap nanodumbbells (AuDGNs), is designed and synthesized via the anisotropic adsorption of polyethyleneimine on Au nanorods to facilitate tip-selective Au growths on nanorod tips for forming mushroom-shaped dumbbell-head structures at both tips and results in dual gaps (intra-head and inter-head gaps) within a single particle. AuDGNs are synthesized in a high yield (>90%) while controlling the inter-head gap size, and the average surface-enhanced Raman scattering (SERS) enhancement factor (EF) value is 7.5 × 108 with a very narrow EF distribution from 1.5 × 108 to 1.5 × 109 for >90% of analyzed particles. Importantly, AuDGNs enable label-free on-particle SERS detection assays through the diffusion of target molecules into the intraparticle gap for different DNA sequences with varying ATGC combinations in a highly specific and sensitive manner without a need for Raman dyes.

Original languageEnglish
Article number2208250
JournalAdvanced Materials
Issue number15
StatePublished - Apr 13 2023
Externally publishedYes


  • anisotropic metal nanostructures
  • label-free SERS detection
  • plasmonic Au dual-gap nanodumbbells
  • plasmonic nanogaps
  • single-particle SERS assays
  • surface-enhanced Raman scattering


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