Highly sensitive C-reactive protein (CRP) assay using metal-enhanced fluorescence (MEF)
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Fluorescence has been extensively employed in the area of diagnostic immunoassays. A significant enhancement of fluorescence can be achieved when noble metal nanoparticles are placed in close proximity to fluorophores. This effect, referred to as metal-enhanced fluorescence (MEF), has the potential to produce immunoassays with a high sensitivity and a low limit of detection (LOD). In this study, we investigate the fluorescence enhancement effect of two different nanoparticle systems, large spherical silver nanoparticles (AgNPs) and gold edge-coated triangular silver nanoplates, and both systems were evaluated for MEF. The extinction properties and electric field enhancement of both systems were modeled, and the optimum system, spherical AgNPs, was used in a sandwich immunoassay for human C-reactive protein with a red fluorescent dye label. A significant enhancement in the fluorescence was observed, which corresponded to an LOD improvement of ~19-fold compared to a control assay without AgNPs.
KeywordsMetal nanoparticles Silver nanoparticles Metal-enhanced fluorescence C-reactive protein Immunoassay Biomedical Instrumentation
This material is based upon works supported by the Science Foundation Ireland under Grant No. 10/CE/B1821. Furthermore, we thank Matthias Zeisberger for the access to the simulation software.
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