Polyelectrolyte layers fluorescence enhancement

Figure 19.7A reports the fluorescent enhancement of the conjugated polymer emitter for structure I when it is deposited on top of various thicknesses of polyelectrolyte spacers for silver treated versus untreated substrates. The fluorescence increases nearly 40 fold for 2 bilayers (roughly 4-6 nm) and then drops though it remains dramatically enhanced even for as much as 13 bi layers (25 nm). 

N. Akbay, J.R. Lakowicz, K. Ray, Distance-dependent metal-enhanced intrinsic fluorescence of proteins using polyelectrolyte layer-by-layer assembly and aluminum nanoparticles. J. Phys. Chem. C 116, 10766-10773 (2012)... 

In order to achieve plasmonic enhancement of fluorescence it is important first of all to establish a deposition technique which can yield reproducible substrates with the desired value. We have carried out a study, where this was achieved using charged polyelectrolyte (PEL) layers which were deposited using a layer-by-layer (LbL) technique and which facilitate uniform and reproducible deposition of metal NPs on a range of surfaces. This is a generic technique which also enables the deposition of highly accurate fluorophore-NP spacer layers as discussed in section... 

Very recently Bawendi and co-workers [4] reported about fivefold increase in the observed fluorescence intensity of single CdSe/ZnS nanocrystalls (NCs) and striking reduction in their fluorescence blinking behavior due to interactions with a rough metal film. The distance-dependent enhancement and quenching of NC fluorescence has been observed by us using the layer-by-layer polyelectrolyte deposition technique to insert well-defined spacer between gold colloidal films and NCs [5] with maximum enhancement for the 9-layer spacer ( 11 nm in thickness). 

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