Surface-Enhanced Raman Scattering Substrates Based on Self-Assembled PEGylated Gold and Gold鈥揝ilver Core鈥揝hell Nanorods
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- 作者：Boris N. Khlebtsov ; Vitaly A. Khanadeev ; Mikhail Yu. Tsvetkov ; Victor N. Bagratashvili ; Nikolai G. Khlebtsov
- 刊名：Journal of Physical Chemistry C
- 出版年：2013
- 出版时间：November 7, 2013
- 年：2013
- 卷：117
- 期：44
- 页码：23162-23171
- 全文大小：606K
- 年卷期：v.117,no.44(November 7, 2013)
- ISSN：1932-7455
文摘
For routine laboratory practice, surface-enhanced Raman scattering (SERS) spectroscopy must be simple, inexpensive, stable for a long time, and reproducible. In this study, we mixed 1 渭L of PEGylated silver-coated gold nanorods (Au鈥揂g NRs) with 1 渭L of Raman reporters to obtain, after deposition on a silicon wafer and drying at room temperature for 5 min, a self-assembled NR monolayer with incorporated Raman molecules. In addition, PEGylated NR powders were fabricated and used for SERS in two options. In one, they were used to prepare SERS colloids with a desired NR concentration in a matter of seconds; in the other, they were directly dissolved in a drop of analyte and were then deposited on a silicon wafer. We investigated the SERS spectra of rhodamine 6G (R6G) and the analytical enhancement factor (AEF) as a function of silver shell thickness and NR concentration at 633 nm laser excitation. A very thin (2 nm) silver coating of Au NRs was sufficient to increase the AEF from 103 for Au NRs to 2.5 脳 104 for composite Au鈥揂g NRs. The increase in the NR concentration from 2 to 14 g/L of Au gave a 3-fold increase in the SERS intensity but did not affect the AEF. Three-dimensional finite-difference time-domain simulations confirmed that the electromagnetic mechanism of AEF enhancement for silver-coated NRs was due to the generation of hotspots near the end-to-end and end-to-side nanoparticle contacts. The estimated cost of all reagents for one SERS measurement is about one cent. Coupled with its simplicity, reproducibility, and low cost, the proposed SERS technique can be recommended for routine chemical or biomedical sensing of small analyte amounts with various substrates, such as glass, polymer films, or even Whatman paper.