Metal-Enhanced Fluoroimmunoassay on a Silver Film by Vapor Deposition

TitleMetal-Enhanced Fluoroimmunoassay on a Silver Film by Vapor Deposition
Publication TypeJournal Article
Year of Publication2005
AuthorsZhang, J., E. Matveeva, I. Gryczynski, Z. Leonenko, and J. Lakowicz
JournalJournal of Physical Chemistry B
Start Page7969
Date Published12/2004

We studied a fluoroimmunoassay using metal-enhanced fluorescence (MEF) detection on silver film generated by vapor deposition method. The morphology of the silver film was controlled through the thickness of the film. A silica layer was coated on the silver film to protect the film and separate the fluorophore from the metal surface. Rabbit immunoglobulin G (IgG) was adsorbed on the silica by physiosorption and then dyelabeled anti-rabbit IgG was bound to the immobilized rabbit IgG. It was observed that the fluorophore was quenched on a thin silver film (2 nm), enhanced on a thick film (>5 nm), and reached saturation (ca. 10 times enhancement) at 20 nm. The MEF was also dependent on the thickness of the silica with a maximum at 10 nm. The lowest lifetime was observed on the 20 nm silver film, which was consistent with the saturation of MEF. These results showed the properties of a silver film needed for a maximum increase of fluorescence intensity in a fluoroimmunoassay. Dependence of the MEF on the emission wavelength was also studied using different dye-labeled anti-rabbit IgGs.

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