Reduction of Self-Quenching in Fluorescent Silica-Coated Silver Nanoparticles

Abstract

This paper reports the development of spherical Ag@SiO 2 nanocomposites in which fluorescein isothiocyanate molecules have been incorporated using a silane coupling agent and a straightforward microemulsion-based synthesis procedure. The photophysical characteristics of core-shell and coreless nanostructures with similar silica shell thickness and fluorophore densities are measured and compared, and show unequivocally that the presence of the silver core decreases the fluorophore lifetime by a factor as high as 4 and that the steady-state fluorescence intensity is increased by a factor as high as 3. The relationship between the enhancement in fluorescence yield and the influence of the silver core on resonance energy transfer processes was examined by fluorescence lifetime and anisotropy measurements. These Ag@SiO 2 core-shell nanoparticles provide higher detectability and lower self-quenching, whereas the faster recycling time offers more robustness toward photobleaching.

The Use of Fluorescent Quenching in Studying the Contribution of Evaporation to Tear Thinning

“…A good correlation between log fitted and log measured efficiency was observed, r 2 ¼ 0.9995, indicating that self quenching of fluorescein is mainly or entirely due to RET, in agreement with evidence from other methods. 48 The two asymptotes of slope 0 and À2 are shown by dashed lines; their intersection gives an estimate of the critical concentration of fluorescein, c 0 in Equation A4, of 0.19%.…”

Metal-Enhanced Fluorescence and FRET in Multilayer Core-Shell Nanoparticles

“…The quantum efficiency of most organic dyes is strongly impacted by self-quenching when their relative concentrations exceed ∼10 −3 M which results from the higher probability of close-range interactions between aggregated dye molecules and longer range intermolecular energy transfer processes (e.g., homotransfer between separated dye molecules and transfer between excited monomers and neighboring quenched aggregates) [64]. While selfquenching directly affects the maximum fluorophore concentration usable in dye-doped silica materials, it was reported by us [40] and others [43] that its severity among other labeled silica matrices can be reduced by the proximity of metallic particles; a phenomenon attributed to a strong decrease in nonradiative decay rates, that is, a reduction in energy transfer between dye molecules. …”

“…The metal core of composite NPs confers them a strong plasmon resonance, and interaction with the surrounding fluorescent molecules greatly improves excitation and emission rates. Moreover, the reduction of the fluorophore's lifetime in the excited state increases photostability and detectability, and the ensuing reduction of self-quenching makes possible the incorporation of higher densities of fluorophore molecules around the metal core [40]. Controlled growth of a dielectric silica shell around the core ensures easy tunability of the dyemetal separation and of the resulting fluorescence enhancement [39].…”

Luminescent single-walled carbon nanotube-sensitized europium nanoprobes for cellular imaging

“…However, the luminescence selfquenching caused by aggregation is not unique to Eu-SWCNT, and has been reported for other luminescent probes. 17,[19][20][21] The confocal images clearly show that time-resolved, red emission of Eu-SWCNT overcomes the endogenous fluorescence contributed by other cellular biomacromolecules (eg, flavins, nicotinamide adenine dinucleotides, collagens, and porphyrins) in the wavelength range 400-550 nm. 22 The involvement of these endogenous biomolecules in the luminescence-quenching process by direct interaction with Eu-SWCNT cannot be neglected, and needs further investigation.…”