Single metal nanoparticles fluorescence enhancement

Importance of Spectral Overlap Fluorescence Enhancement by Single Metal Nanoparticles... 

Shape The radiative emission from molecules confined within metallic nanocavities and on the surface of nanoparticles is of great relevance to biotechnology. In 1986, it has been suggested that fluorescence enhancement and reduced observation volumes could be obtained from small metal apertures (85). Nanocavities of different shapes could induce different surface plasmon (SP) fields. More recently, some studies has been done for different shapes, such as circular (86-90), elliptical (91), coaxial (92), or rectangular (93, 94) metallic nanocavity(95). In 2003, single-molecule detection from a nanocavity was demonstrated (86). However, it might be difficult to position the biospecies in the nanocavities. 

Figure 7.1 (A) Schematic representation of the Metal-Enhanced Fluorescence phenomena (B) FDTD calculations for two silver nanoparticle arrays (d = 100 nm). (C) Wavelength-dependent calculated Ej maximum intensity for silver nanoparticle arrays (d = 100 nm). Geometries and incident field polarization [p-polarized) and propagation direction are shown in the insets. The gap between the nanopaiticles was assumed to be 2 nm in the calculations. (D) Calculated field enhancement as a function of distance for a single silver nanoparticle (d = 100 nm).The inset shows these results as an FDTD E image above the nanoparticle.

In those cases, the ina-eased two photon absorption due to the field enhancement effect clearly outweighs the effects of fluorescence quenching. However, also these experiments had been carried out on submonolayer metallic films. Peleg et al. showed a decreased two photon fluorescence signal frcnn fluorophores close to single gold nanoparticles. ... 

Aslan K, Wu M, Lakowicz JR, Geddes CD (2007) Fluorescent core-shell Ag Si02 nanocomposites for metal-enhanced fluorescence and single nanoparticle sensing platforms. J Am Chem Soc 129 1524-1525... 

Aslan, K., Wu, M., Lakowicz, J. R., Geddes, C. D. (2007). Fluorescent Core-Shell Ag Si02 Nanocomposites for Metal-Enhanced Fluorescence and Single Nanoparticle Sensing Platforms. J. Am. Chem. Soc. 129 1524-1525. 

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