Smart SERS Hot Spots: Single Molecules Can Be Positioned in a Plasmonic Nanojunction Using Host-Guest Chemistry
| Autor: | Wooseup Hwang, Martin Moskovits, So Young Lee, Hyun Woo Kim, Ji Won Ha, Jungho Mun, Gyeongwon Yun, Rumum Rohman, James Brooke Murray, Kangkyun Baek, Junsuk Rho, Nam Hoon Kim, Jeehong Kim, Kimoon Kim |
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| Rok vydání: | 2018 |
| Předmět: |
Analyte
Chemistry Substrate (chemistry) Nanotechnology Hot spot (veterinary medicine) 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Biochemistry Catalysis Silver nanoparticle 0104 chemical sciences symbols.namesake Colloid and Surface Chemistry symbols Molecule 0210 nano-technology Host–guest chemistry Raman spectroscopy Plasmon |
| Zdroj: | Journal of the American Chemical Society. 140(13) |
| ISSN: | 1520-5126 |
| Popis: | Single-molecule surface-enhanced Raman spectroscopy (SERS) offers new opportunities for exploring the complex chemical and biological processes that cannot be easily probed using ensemble techniques. However, the ability to place the single molecule of interest reliably within a hot spot, to enable its analysis at the single-molecule level, remains challenging. Here we describe a novel strategy for locating and securing a single target analyte in a SERS hot spot at a plasmonic nanojunction. The "smart" hot spot was generated by employing a thiol-functionalized cucurbit[6]uril (CB[6]) as a molecular spacer linking a silver nanoparticle to a metal substrate. This approach also permits one to study molecules chemically reluctant to enter the hot spot, by conjugating them to a moiety, such as spermine, that has a high affinity for CB[6]. The hot spot can accommodate at most a few, and often only a single, analyte molecule. Bianalyte experiments revealed that one can reproducibly treat the SERS substrate such that 96% of the hot spots contain a single analyte molecule. Furthermore, by utilizing a series of molecules each consisting of spermine bound to perylene bisimide, a bright SERS molecule, with polymethylene linkers of varying lengths, the SERS intensity as a function of distance from the center of the hot spot could be measured. The SERS enhancement was found to decrease as 1 over the square of the distance from the center of the hot spot, and the single-molecule SERS cross sections were found to increase with AgNP diameter. |
| Databáze: | OpenAIRE |
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