An ideal surface-enhanced Raman scattering (SERS) nanostructure for sensing and imaging applications should induce a high signal enhancement, generate a reproducible and uniform response, and should be easy to synthesize. Many SERS-active nanostructures have been investigated, but they suffer from poor reproducibility of the SERS-active sites, and the wide distribution of their enhancement factor values results in an unquantifiable SERS signal. Here, we show that DNA on gold nanoparticles facilitates the formation of well-defined gold nanobridged nanogap particles (Au-NNP) that generate a highly stable and reproducible SERS signal. The uniform and hollow gap (∼1 nm) between the gold core and gold shell can be precisely loaded with a quantifiable amount of Raman dyes. SERS signals generated by Au-NNPs showed a linear dependence on probe concentration (R2>0.98) and were sensitive down to 10 fM concentrations. Single-particle nano-Raman mapping analysis revealed that >90% of Au-NNPs had enhancement factors greater than 1.0 × 10 8, which is sufficient for single-molecule detection, and the values were narrowly distributed between 1.0 × 108 and 5.0 × 108.
Bibliographical noteFunding Information:
D-K.L. acknowledges financial support from the CJ Pharmaceutical Research Institute. K-S.J. acknowledges support by the Public Welfare & Safety Research Program through NRF funded by MEST (2010-0020-795).
Y.D.S. was supported by KRICT (KK-0904-02, SI-1110), the Nano R&D Program (No. 2009-0082861), the Pioneer Research Center Program of NRF (No. 2009-0081511), the Development of Advanced Scientific Analysis Instrumentation Project of KRISS by MEST and the Eco-technopia 21 Project by KME. J-M.N. was supported by the 21C Frontier Functional Proteomics Project (FPR08-A2-150) and the Nano R&D program (2008-02890) through the National Research Foundation of Korea (NRF) from the Ministry of Education, Science and Technology. The authors would also like to acknowledge financial support from the Industrial Core Technology Development Program of the Ministry of Knowledge Economy (nos 10033183 and 10037397) and the KRICT OASIS Project from the Korea Research Institute of Chemical Technology.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering