Silver Island Films SiFs

A number of promising metal structures for fluorescence signal enhancement have been proposed silver island films (SIFs) that provide about 5-15-fold enhancement [89], fractal-like structures that resulted in stronger enhancements at specific hot spots [90-92], and SIFs deposited on silver or gold films with about 50-fold enhancement [93, 94], Recently, it was found that strong enhancement on a gold film based plasmonic platform may change even the shape of the emission spectrum [95],... 

Figure 1.3. (A) Photographs of silver island films (SIFs) deposited onto glass and plastic supports. (B) Normalized absorbance of zinc, copper, gold and silver nanostructured particles on a glass support. Atomic force microscope images of SIFs on (C) glass (D) plastic support.

Figure 5.3 Atomic Force Microscopy (AFM) images of two Silver Island Film (SIF) coated glass slides (A B), showing the variation in size and density that can be obtained by altering the dip coating conditions. Slides were produced by LI-COR Biosciences and imaged at the University of Nebraska-Lincoln.

Figure 10.3A) for the green sensor dye (GR), before exposure to UV light on silver island films (SiF) and glass substrates (GL), respectively. The calculation of the MEO oxygen yield) of the photosensitizer is as follows... 

Both Geddes and the Lakowicz group s have investigated the metal-enhanced fluorescence of fluorophores on silver island films (SIFs) [11,26,27] and variously aggregated silver nanoparticles in solution [28,29]. One example of enhancement on SIFs is discussed below [26]. In this work the distance-dependent MEF of a monolayer of sulforfiodamine B (SRB) on SIFs was studied. A SRB monolayer was electrostatically incorporated into the Langmuir-Blodgett (LB) layers of octadecylamine (ODA) deposited... 

In an exemplary work, Lakowicz and co-workers have used the MEF strategy to increase the detectability of Cy3- and Cy5-labeled DNA on solid substrates covered with silver island films (SIFs) and have found a five- to tenfold increase in intensity from the silver particle-coated quartz substrate compared with uncoated quartz (Fig. 18) [120]. As one would expect from the aforementioned, these enhanced intensities have been accompanied by dramatically shortened fluorescence lifetimes, which in turn has led to a significantly higher photostability of Cy3 and Cy5 in the presence of the silver nanoparticles (AgNPs). In this study, the SIFs have been composed of silver nanoparticles with a diameter of 100-300 nm. 

ENHANCED EMISSION FROM LOW AND HIGH QUANTUM YIELD SPECIES USING SILVER ISLAND FILMS (SiFs)... 

We examined the emission of DNA in micron thick samples between quartz plates and between silver island films (SiFs). When a solution of DNA is examined between two quartz slides the emission is barely detectable (Figure 12). There is a dramatic increase in intrinsic emission for the DNA between SiFs. In this experiment, the information is only qualitative because the DNA is not bound to the surfaces and only a... 

Figure 10.4 Absorption spectra and AFM image of SiFs before light after light showing no effect on the silvered surface by 102. SiFs — Silver island Films. Light- UV exposure. Adopted irom ref [25].

Figure 10.8 Real color photographs of dihydroethidium (DFIE) and Acridine emission from glass and SiFs, before and after 2 mins light exposure (sensitization). Light exposure source was a 100 W mercury lamp. A.ex = 473 nm. SiFs - Silver Island Films. Adopted from ref [31].

Figure 10.9 Sample architecture for the distance dependence of metal-enhanced Superoxide generation (Top), and graphical representation of the interpretation of metal-enhanced superoxide generation with an enhanced and distance dependent excitation rate (Bottom). F - Fluorophore, MEF - Metal-Enhanced Fluorescence, MEP — Metal-enhanced Phosphorescence, SiFs — Silver Island Films. EF- Enhancement factor = I Silver /I Glass. Adopted from ref [31 ].

SiFs (Bottom - insert). Ag - Silver. SiFs - Silver Island Film. Reproduced from Applied Physics Letters 88 173104 (2006). 

Figure 1.9. (A) E-type Fluorescence and phosphorescence emission spectra, ex = 473 nm, of Eosin in a cuvette at different temperatures. Insert Eosin immobilized in PVA sandwiched between two silvered and unsilvered slides at 25C EF - Enhancement Factor. RT - Room Temperature. (B) experimental sample geometry. (C) Real-color photographs of Eosin emission from glass and SIFs, before and after 2 mins heating, ex = 473 mn. SIFs - Silver Island Films. The real- color photographs were taken through an emission filter (488 mn razor edge).

We also studied the photostability of FITC on the fractal silver stuface, silver island films, and uncoated quartz. Although the relative photobleaching is higher on fractal silver, the increased rate of photobleaching is less than the increase in intensity (Figure 45). From the areas under these curves we estimate 16-fold and 160-fold more photons can be detected from the FITC-HSA on SiFs or fractal silver, respectively, relative to quartz, before photobleaching. 

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