Distance dependence of single-fluorophore quenching by gold nanoparticles studied on DNA origami.
ABSTRACT We study the distance-dependent quenching of fluorescence due to a metallic nanoparticle in proximity of a fluorophore. In our single-molecule measurements, we achieve excellent control over structure and stoichiometry by using self-assembled DNA structures (DNA origami) as a breadboard where both the fluorophore and the 10 nm metallic nanoparticle are positioned with nanometer precision. The single-molecule spectroscopy method employed here reports on the co-localization of particle and dye, while fluorescence lifetime imaging is used to directly obtain the correlation of intensity and fluorescence lifetime for varying particle to dye distances. Our data can be well explained by exact calculations that include dipole-dipole orientation and distances. Fitting with a more practical model for nanosurface energy transfer yields 10.4 nm as the characteristic distance of 50% energy transfer. The use of DNA nanotechnology together with minimal sample usage by attaching the particles to the DNA origami directly on the microscope coverslip paves the way for more complex experiments exploiting dye-nanoparticle interactions.
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ABSTRACT: An aureate dye: Confined electromagnetic fields in DNA-templated gold nanoparticle dimers were tuned to engineer the fluorescence properties of organic dyes in water. Purified suspensions of hybrid metal-organic chromophores featured unprecedented photophysical properties, such as a short lifetime and low quantum yield but high brightness.Angewandte Chemie International Edition 10/2012; 51(44):11083-7. · 13.73 Impact Factor
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ABSTRACT: We report a localized surface plasmon enhanced upconversion luminescence in Au/SiO2/Y2O3:Yb(3+),Er(3+) nanoparticles when excited at 980 nm. By adjusting the silica spacer's thickness, a maximum 9.59-fold enhancement of the green emission was obtained. Effect of the spacer distance on the Au-Y2O3:Yb(3+), Er(3+) green upconversion mechanism was numerically simulated and experimentally demonstrated. In theory for radiative decay and excitation rates, they can be largely enhanced at the spacer thicknesses of less than 70 and 75 nm, respectively, and the quenching can be caused by the non-radiative energy transferring at the distance of less than 55 nm.Theranostics 01/2013; 3(4):282-8. · 7.81 Impact Factor
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ABSTRACT: We introduce self-assembled nanoantennas to enhance the fluorescence intensity in a plasmonic hotspot of zeptoliter volume. The nanoantennas are prepared by attaching one or two gold nanoparticles (NPs) to DNA origami structures, which also incorporated docking sites for a single fluorescent dye next to one NP or in the gap between two NPs. We measured the dependence of the fluorescence enhancement on NP size and number and compare it to numerical simulations. A maximum of 117-fold fluorescence enhancement was obtained for a dye molecule positioned in the 23-nanometer gap between 100-nanometer gold NPs. Direct visualization of the binding and unbinding of short DNA strands, as well as the conformational dynamics of a DNA Holliday junction in the hotspot of the nanoantenna, show the compatibility with single-molecule assays.Science 10/2012; 338(6106):506-10. · 31.20 Impact Factor