Tuning and Maximizing the Single-Molecule Surface-Enhanced Raman Scattering from DNA-Tethered Nanodumbbells
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- 作者：Jung-Hoon Lee ; Jwa-Min Nam ; Ki-Seok Jeon ; Dong-Kwon Lim ; Hyoki Kim ; Sunghoon Kwon ; Haemi Lee ; Yung Doug Suh
- 刊名：ACS Nano
- 出版年：2012
- 出版时间：November 27, 2012
- 年：2012
- 卷：6
- 期：11
- 页码：9574-9584
- 全文大小：660K
- 年卷期：v.6,no.11(November 27, 2012)
- ISSN：1936-086X
文摘
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鈥揂g core鈥搒hell 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鈥?0 nm pair to a 50鈥?0 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 脳 1013 (average value = 1.8 脳 1013) was obtained and the EF values of analyzed particles were narrowly distributed between 1.9 脳 1012 and 5.9 脳 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.