Metal-enhanced fluoroimmunoassay on a silver film by vapor deposition

Jian Zhang, Evgenia Matveeva, Ignacy Gryczynski, Zoya Leonenko, Joseph R. Lakowicz

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35 Scopus citations


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.

Original languageEnglish
Pages (from-to)7969-7975
Number of pages7
JournalJournal of Physical Chemistry B
Issue number16
StatePublished - 28 Apr 2005


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