The ability to create colloidal nanoparticle assemblies with finely tuned topological parameters is critical to the development of efficient and reliable plasmonic platforms, which can enable applications such as surface-enhanced Raman scattering (SERS).

Sang Woo Han and colleagues, KAIST, Daejeon, Korea, have developed a simple aqueous synthesis method for the preparation of stable gold nanoparticle clusters with finely controlled sizes of the constituent nanoparticles, without changes in the number of nanoparticles and the size of interparticle gaps (pictured). Accordingly, the exclusive influence of nanoparticle size on the SERS activity of the nanoparticle clusters could be precisely explored.

The team found that the particle-size dependent SERS activity of the nanoparticle clusters can be correlated with the relative contributions of the near-field enhancement and areal density of hot spots in the clusters. The researchers expect that this study will help to design ideal nanoparticle-assembly-based plasmonic platforms for different applications, such as bio-, chemical, and environmental sensing, as well as bioimaging.

• Colloidal Clusters of Plasmonic Nanoparticles with Controlled Topological Parameters,
  Seunghoon Lee, Seungwoo Kang, Jaeyoung Kim, Younghyun Wy, Sang Woo Han,
  ChemNanoMat 2017.
  DOI: 10.1002/cnma.201700152