Polyelectrolyte Layer-by-Layer Assembly To Control the Distance between Fluorophores and Plasmonic Nanostructures

• DOI: 10.1021/cm071510w
• Publication Date: 2007-11-03T05:00:35Z
• Authors: Krishanu Ray; Ramachandram Badugu; Joseph R. Lakowicz
• Keywords: Allylamine; Layer by layer

In the past several years we have demonstrated metal-enhanced fluorescence (MEF) and significant changes in photophysical properties of fluorophores presence metallic nanostructures nanoparticles. MEF is largely dependent on factors, such as chemical nature, size, shape nanostructure, its distance from interrogating fluorophore. Herein, elucidate potential layer-by-layer (LbL) assembly to understand dependence nature sulforhodamine B (SRB) assembled plasmonic nanostructured surfaces [in form Silver Islands films (SIFs)]. The varied proximity SIF was controlled by constructing different numbers alternate layers poly(styrene sulfonate) (PSS) poly(allylamine hydrochloride) (PAH). An anionic laser dye SRB could be electrostatically attached positively charged PAH layer. Orientation probe molecule adsorbed PSS/PAH-layered determined polarized absorption spectroscopy. observed tilt angle transition dipole moment with respect surface normal 40°. Our results show that indeed distance-dependent. Accordingly, a maximum ∼6-fold increase intensity monolayer at ∼9 nm metal-nanostructured surface, enhancement decreasing down ∼1.5-fold about 30 separation distance. Consistently, minimum lifetimes were 4-fold shorter than those glass slides without silver, being nearly same for 15 PSS/PAH assembly. intensity–time decays analyzed lifetime distribution model underpin effect metal–fluorophore interaction nanometric range. present study provides improved understanding between and, more importantly, their where used robust, easy, inexpensive electrostatic LbL bottom-up nanofabrication technique control surface.