AVS 50th International Symposium
    Nanometer Structures Friday Sessions
       Session NS+BI-FrM

Paper NS+BI-FrM5
Interaction of Fluorescent Molecules with Metallic Nanoparticles Mediated by Biospecific Interactions

Friday, November 7, 2003, 9:40 am, Room 317

Session: Nanotechnology and Biology
Presenter: V.H. Perez-Luna, Illinois Institute of Technology
Authors: V.H. Perez-Luna, Illinois Institute of Technology
K. Aslan, Illinois Institute of Technology
I. Severcan, Illinois Institute of Technology
Correspondent: Click to Email
Metallic nanoparticles affect the emission characteristics of fluorophores located in their proximity. Here we exploit this strong influence in a system where gold nanoparticles are functionalized with biotin. Preparation of biotinylated gold nanoparticles is performed in the present of a nonionic surfactant to ensure their stability. The interaction of these biotinylated gold nanoparticles with Alexa488-labeled anti-biotin in solution was studied by optical absorption spectroscopy and fluorescence spectroscopy. It was found that reduction or enhancement of fluorescence emission could result when Alexa488-labeled anti-biotin interacted with biotinylated gold nanoparticles. This depended on the surface coverage of biotin groups, the concentration of antibody and the concentration of biotinylated gold nanoparticles. Introduction of soluble biotin to dissociate the bound antibodies from the surface of the nanoparticles reversed the signals observed previously. These observations can be explained in terms of the competing effects that metallic nanoparticles can have on emission of fluorescence. Quenching of fluorescence can occur when the fluorophores are in close proximity to the metallic surfaces. However, metallic nanoparticles can also enhance the excitation intensity due to concentration of the incident field in the vicinity of the nanoparticles. Additionally, metallic surfaces can also provide additional pathways for radiative decay of the fluorophores. These concepts will have important implications for novel materials in fluorescence detection.