Silver鈥揋old Nanocomposite Substrates for Metal-Enhanced Fluorescence: Ensemble and Single-Molecule Spectroscopic Studies
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- 作者：Sharmistha Dutta Choudhury ; Ramachandram Badugu ; Krishanu Ray ; Joseph R. Lakowicz
- 刊名：The Journal of Physical Chemistry C
- 出版年：2012
- 出版时间：March 1, 2012
- 年：2012
- 卷：116
- 期：8
- 页码：5042-5048
- 全文大小：475K
- 年卷期：v.116,no.8(March 1, 2012)
- ISSN：1932-7455
文摘
In recent years, there has been a growing interest in the studies involving the interactions of fluorophores with plasmonic nanostructures or nanoparticles. These interactions lead to several favorable effects such as increase in the fluorescence intensities, increased photostabilities, and reduced excited-state lifetimes that can be exploited to improve the capabilities of present fluorescence methodologies. In this regard, we report the use of newly developed silver鈥揼old nanocomposite (Ag鈥揂u鈥揘C) structures as substrates for metal-enhanced fluorescence (MEF). The Ag鈥揂u鈥揘C substrates have been prepared by a one-step galvanic replacement reaction from thin silver films coated on glass slides. This approach is simple and suitable for the fabrication of MEF substrates with large area. We have observed about 15-fold enhancement in the fluorescence intensity of ATTO655 from ensemble fluorescence measurements using these substrates. The fluorescence enhancement on the Ag鈥揂u鈥揘C substrates is also accompanied by a reduction in the fluorescence lifetime of ATTO655, which is consistent with the fluorophore鈥損lasmon coupling mechanism. Single-molecule fluorescence measurements have been performed to gain more insight into the metal鈥揻luorophore interactions and to unravel the heterogeneity in the interaction of individual fluorophores with the fabricated substrates. The single-molecule studies are in good agreement with the ensemble measurements and show maximum enhancements of 50-fold for molecules located in proximity to the 鈥渉otspots鈥?on the substrates. In essence, the Ag鈥揂u鈥揘C substrates have a very good potential for various MEF applications.