title: Novel multicolor fluorescently labeled silica nanoparticles for interface fluorescence resonance energy transfer to and from labeled avidin.
abstract: Fluorescent silica nanoparticles (SiNPs) were prepared by covalent attachment of fluorophores to the amino-modified surface of SiNPs with a typical diameter of 15 nm. The SiNPs are intended for use in novel kinds of fluorescence resonance energy transfer (FRET)-based affinity assays at the interface between nanoparticle and sample solution. Various labels were employed to obtain a complete set of colored SiNPs, with excitation maxima ranging from 337 to 659 nm and emission maxima ranging from 436 nm to the near infrared (710 nm). The nanoparticles were characterized in terms of size and composition using transmission electron microscopy, thermogravimetry, elemental analysis, and dynamic light scattering. The surface of the fluorescent SiNPs was biotinylated, and binding of labeled avidin to the surface was studied via FRET in two model cases. In the first, FRET occurs from the biotinylated fluorescent SiNP (the donor) to the labeled avidin (the acceptor). In the second, FRET occurs in the other direction. Aside from its use in the biotin-avidin system, such SiNPs also are believed to be generally useful fluorescent markers in various kinds of FRET assays, not the least because the fluorophore is located on the surface of the SiNPs (and thus always much closer to the second fluorophore) rather than being doped deep in its interior.
authors.affiliation: Institute of Analytical Chemistry, Chemo and Biosensors, University of Regensburg, 93040 Regensburg, Germany.
authors.forename: Sayed M
authors.initials: SM
authors.lastname: Saleh
authors.forename: Rainer
authors.initials: R
authors.lastname: Müller
authors.forename: Heike S
authors.initials: HS
authors.lastname: Mader
authors.forename: Axel
authors.initials: A
authors.lastname: Duerkop
authors.forename: Otto S
authors.initials: OS
authors.lastname: Wolfbeis
mesh_terms: D001360:Avidin / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry; D019793:Fluorescein / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer / Q000295:instrumentation* / Q000379:methods; D005456:Fluorescent Dyes / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012235:Rhodamines / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D005456:Fluorescent Dyes; C436864:Oregon Green 488 carboxylic acid; D012235:Rhodamines; D001360:Avidin; D012822:Silicon Dioxide; C029773:rhodamine B; D019793:Fluorescein