Improved method for fluorophore deposition atop a polyelectrolyte spacer for quantitative study of distance-dependent plasmon-assisted luminescence

摘要

A layer-by-layer deposited polyelectrolyte spacer is used to attach CdSe nanocrystals (NCs), dye molecules and fluorescein-labelled bovine serum albumin (BSA-FITC) to flat glass and rough silver island surfaces in order to study the effect of spacer thickness on homogeneity and surface concentration of fluorophore coverage. Three different methods of fluorophore deposition atop the polyelectrolyte spacer are examined using steady-state spectroscopy, fluorescent microscopy and statistical analysis. The best homogeneous covering with nanocrystals at a controllable concentration was found for deposition from a solution of NCs which are electrostatically bound to polyelectrolyte macromolecules. This fluorophore deposition method allows one to avoid artefacts and to evaluate the fluorescence enhancement factor of BSA-FITC adsorbed on silver island films.