title: Metal-enhanced fluoroimmunoassay on a silver film by vapor deposition.
abstract: 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 dye-labeled 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.
authors.affiliation: Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, Maryland 21201, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Evgenia
authors.initials: E
authors.lastname: Matveeva
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
authors.forename: Zoya
authors.initials: Z
authors.lastname: Leonenko
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Lakowicz
mesh_terms: D019411:Clinical Laboratory Techniques; D015200:Fluoroimmunoassay; D018625:Microscopy, Atomic Force; D049329:Nanostructures; D012834:Silver
chemical_list: D012834:Silver