Fluorescent Lifetime Quenching near d = 1.5 nm Gold Nanoparticles: Probing NSET Validity (original) (raw)
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Quenching and Blinking of Fluorescence of a Single Dye Molecule Bound to Gold Nanoparticles
The Journal of Physical Chemistry B, 2006
A fluorescein derivative (SAMSA) bound to gold nanoparticles of different diameters is investigated by timeresolved fluorescence at the single molecule level in a wide dynamic range, from nanosecond to second time scale. The significant decrease of both SAMSA excited state lifetime and fluorescence quantum yield observed upon binding to gold nanoparticles can be essentially traced back to an increase of the nonradiative deactivation rate, probably due to energy transfer, that depends on the nanoparticle size. A slow single molecule fluorescence blinking, in the ms time scale, has a marked dependence on the excitation intensity both under single and under two photon excitation. The blinking dynamics is limited by a low probability nonlinear excitation to a high energy state from which a transition to a dark state occurs. The results point out a strong coupling between the vibro-electronic configuration of the dye and the plasmonic features of the metal nanoparticles that provide dye radiationless deactivation channels on a wide dynamic range.
ACS Nano, 2012
Non-radiative energy transfer to metal nanoparticles is a technique used for optical based distance measurements which is often implemented in sensing. Both Förster resonant energy transfer (FRET) and nanometal surface energy transfer (NSET) mechanisms have been proposed for emission quenching in proximity to metal nanoparticles. Here quenching of emission of colloidal quantum dots in proximity to a monolayer of gold nanoparticles is investigated. Five differently sized CdTe quantum dots are used to probe the wavelength dependence of the quenching mechanism as their emission peak moves from on resonance to off resonance with respect to the localized surface plasmon peak of the gold nanoparticle layer. The gold nanoparticle concentration and distance dependences of energy transfer are discussed.
The Journal of Physical Chemistry C, 2018
We study the effects of metal-enhanced fluorescence (MEF) on rhodamine B fluorophore by nanoparticles of varied shapes. The avidin−biotin system was used as spacer to connect the fluorophore to the surface of nanoparticles. Fluorescence lifetime image microscopy (FLIM) was used to detect emission lifetime for dye molecules on single nanoparticles. Spherical gold particles diameter of 60 and 170 nm, respectively, cube length of 70 nm, and rhombic dodecahedron (RD) diameter of 63 nm were used. In the measured emission curves of rhodamine B, we obtained a short component with lifetime 16−26 ps attributed to the fluorophore under influence of the local electric field of gold nanoparticle and energy dissipation to nanoparticle. The second lifetime is 200, 270, 280, and 330 ps for 170 nm sphere, 70 nm cube, 63 nm RD, and 60 nm sphere, respectively. This component is referred to as the bright mode of nanoparticle which is coupled to the excited dye molecule and transfers energy back to the fluorophore. On the basis of the large amplitude obtained for the short lifetime component, the effect of MEF was great. The avidin−biotin assembly serves as a biospacer in the MEF applications. Moreover, the MEF effect on the Ag shell gold nanoparticle is studied. Various thicknesses of Ag shell around 40 nm diameter gold core nanoparticles were synthesized. In these Au@Ag−R nanoparticles, time constants obtained in rhodamine B emission curves are τ 1 /τ 2 = 15/210, 23/240, 26/251, 21/246, 25/255 ps for Ag shell thickness of 4, 6, 7.5, 13, and 16 nm, respectively. Because of this multiple exponential decay behavior, we derived a kinetic model for the MEF process and calculated the rate constants of energy transfer between the dye molecules and the Au@Ag nanoparticle. As rhodamine B is excited, it can transfer energy to Au nanoparticle and also dissipates energy to Ag shell via nanosurface energy transfer (NSET), leading to severe fluorescence quenching. This results in low enhancement factors of fluorescence in this core−shell system. According to the experimental lifetime data, the NSET rate constant for the energy dissipation to Ag surface is estimated to be (4−6.6) × 10 10 s −1 .
Journal of Nanomedicine & Nanotechnology, 2012
The light absorption and emission characteristics of Gold Nanoparticles (GNPs) are exploited in detection and treatment of cancer. The properties of Nanoparticles (NPs) give them high potential for use in various medical applications, particularly in diagnostics and therapy where they promise increased sensitivity, speed, and costeffectiveness. The Ultraviolet-Visible and fluorescence properties of non-functionalized GNPs have not thus far been comprehensively documented. This study evaluated the absorption and fluorescence spectra for solutions of GNPs at different concentrations.
We consider the effect of gold nanospheres of subwavelength sizes on the decay and energy transfer rates of quantum systems placed in the proximity of these nanospheres. We find that, for the sphere sizes considered in this contribution, the radiative decay rate is barely affected by the presence of the nanosphere, whereas the non-radiative decay rate is greatly enhanced due to energy transfer from the quantum system to the nanosphere, leading to a strong quenching of the emission of the quantum system. The emission wavelength of the quantum emitter and its intrinsic quantum yield play an important role and the impact of both has to be considered together when investigating their effect on the non-radiative decay rate. The energy transfer process from the emitter to the nanosphere presents a complicated distance dependence, with a r −6 regime, characteristic of the Förster energy transfer mechanism, but also exhibiting other distance dependence regimes. In the case of a donor-acceptor pair of quantum systems in the presence of a gold nanosphere, the donor couples strongly to the nanosphere, acting as an enhanced dipole; the donor-acceptor energy transfer rate then follows a Förster trend, with an increased Förster radius. The coupling of the acceptor to the nanosphere has a different distance dependence, and it does not follow a Förster-type trend. The angular dependence of the energy transfer efficiency between donor and acceptor has a strong dipoledipole trend for small spheres and deviating from it for larger spheres, especially when the donor and acceptor are on opposite sides of the sphere. The spectral overlap of the donor emission, acceptor absorption and gold nanosphere extinction/scattering shows an interesting trend in that the largest Förster radius is obtained when the donor emission and acceptor absorption maxima are somewhat red-shifted from the localized surface plasmon peak in the extinction spectrum of the gold nanosphere, being located between it and the near-field scattering maximum.
The Journal of Physical Chemistry C
The surface plasmon modes of metal nanoparticles provide a way to efficiently enhance the excitation and emission from a fluorescent dye. We have employed DNA-directed assembly to prepare dimers of gold nanoparticles and used their longitudinally coupled plasmon mode to enhance the fluorescence emission of an organic red-emitting dye, Atto-655. The plasmonenhanced fluorescence of this dye using dimers of 80 nm particles was measured at single molecule detection level. The top enhancement factors were above 1000-fold in 71% of the dimers within a total of 32 dimers measured, and, in some cases, they reached almost 4000-fold, in good agreement with model simulations. Additionally, fluorescence lifetime correlation analysis enabled the separation of enhanced from non-enhanced emission simultaneously collected in our confocal detection volume. This approach allowed us to recover a short relaxation component exclusive to enhanced emission that is attributed to the interaction of the dye with DNA in the interparticle gaps. Indeed, the frequency of enhancement events is larger than expected from the volume occupancy of the gap region, thus suggesting that interaction of the dye with DNA linkers favors the observation of emission enhancement in our dimer particles.
Energy transfer between a biological labelling dye and gold nanorods
Methods and Applications in Fluorescence, 2013
We have demonstrated energy transfer between a biological labeling dye (Alexa Fluor 405) and gold nanorods experimentally and theoretically. The ‡uorescence lifetime imaging microscopy and density matrix method are used to study a hybrid system of dye and nanorods under one-and two-photon excitations. Energy transfer between dye and nanorods via the dipole-dipole interaction is found to cause a decrease in the ‡uorescence lifetime change. Enhanced energy transfer from dye to nanorods is measured in the presence of an increased density of nanorods. This study has potential applications in ‡uorescence lifetime-based intra-cellular sensing of bio-analytes as well as nuclear targeting cancer therapy.
Nano Letters, 2007
We combine interferometric detection of single gold nanoparticles, single molecule microscopy, and fluorescence lifetime measurement to study the modification of the fluorescence decay rate of an emitter close to a nanoparticle. In our experiment, gold particles with a diameter of 15 nm were attached to single dye molecules via double-stranded DNA of different lengths. Nanoparticle-induced lifetime modification (NPILM) has promise in serving as a nanoscopic ruler for the distance range well beyond 10 nm, which is the upper limit of fluorescence resonant energy transfer (FRET). Furthermore, the simultaneous detection of single nanoparticles and fluorescent molecules presented in this work provides new opportunities for single molecule biophysical studies.
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Journal of Molecular Structure, 2003
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