Time-resolved fluorescence emission spectra of labeled phospholipid vesicles, as observed using multi-frequency phase-modulation fluorometry

Lakowicz, Joseph R.; Cherek, Henryk; Laczko, Gabor; Gratton, Enrico

doi:10.1016/0005-2736(84)90419-x

Cited by 47 publications

(37 citation statements)

References 24 publications

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“…For example, solvent-sensitive fluorophores like prodan or laurdan display blue-shifted emission in solid-phase membranes and red-shifted emission above the phase transition temperatures (70,71). It is also known that polarity-sensitive fluorophores display time-dependent spectral shifts when bound to proteins or membranes (72,73).…”

Section: Solvent Effects and Spectral Shiftsmentioning

confidence: 99%

Radiative Decay Engineering: Biophysical and Biomedical Applications

Lakowicz

2001

Analytical Biochemistry

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Fluorescence spectroscopy is a widely used research tool in biochemistry and molecular biology. Fluorescence has also become the dominant method enabling the revolution in medical diagnostics, DNA sequencing, and genomics. To date all the fluorescence observables, including spectral shifts, anisotropies, quantum yields, and lifetimes, have all been utilized in basic and applied uses of fluorescence. In this forward-looking article we describe a new opportunity in fluorescence, radiative decay engineering (RDE). By RDE we mean modifying the emission of fluorophores or chromophores by increasing or decreasing their radiative decay rates. In most fluorescence experiments the radiative rates are not changed because these rates depend on the extinction coefficient of the fluorophore. This intrinsic rate is not changed by quenching and is only weakly dependent on environmental effects. Spectral changes are usually caused by changes in the nonradiative rates resulting from quenching or resonance energy transfer. These processes affect the emission by providing additional routes for decay of the excited states without emission. In contrast to the relatively constant radiative rates in free solution, it is known that the radiative rates can be modified by placing the fluorophores at suitable distances from metallic surfaces and particles. This Review summarizes results from the physics literature which demonstrate the effects of metallic surfaces, colloids, or islands on increasing or decreasing emissive rates, increasing the quantum yields of low quantum yield chromophores, decreasing the lifetimes, and directing the typically isotropic emission in specific directions. These effects are not due to reflection of the emitted photons, but rather as the result of the fluorophore dipole interacting with free electrons in the metal. These interactions change the intensity and temporal and spatial distribution of the radiation. We describe the unusual effects expected from increases in the radiative rates with reference to intrinsic and extrinsic biochemical fluorophores. For instance, the decreased lifetime can result in an effective increase in photostability. Proximity to nearby metallic surfaces can also increase the local field and modify the rate of excitation. We predict that the appropriate localization of fluorophores near particles can result in usefully high emission from "nonfluorescent" molecules and million-fold increases in the number of photons observable from each fluorophore. We also describe how RDE can be applied to medical testing and biotechnology. As one example we predict that nearby metal surfaces can be used to increase the low intrinsic quantum yields of nucleic acids and make unlabeled DNA detectable using its intrinsic metal-enhanced fluorescence.

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Section: Solvent Effects and Spectral Shiftsmentioning

confidence: 99%

Radiative Decay Engineering: Biophysical and Biomedical Applications

Lakowicz

2001

Analytical Biochemistry

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“…The analysis of timedependent spectral width (TDSW) helps us to distinquish between them. Examples for TDSW can be found in several articles, see [1,17,18]. A TDSW gives information about the underlying processes.…”

Section: Resultsmentioning

confidence: 99%

Relation Between Fluorescence Decays and Temporal Evolution of Excited States

et al. 2006

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A differential equation system describing the temporal evolution of excited substates and fluorescence emission were tested using a DOPRI algorithm. The numerical solutions show that there is significant difference in the measurable parameters according to the type of connectivity among the excited substates. In the globally connected case, the fluorescence emission exhibits a double exponential behavior, and the first moment of the emitted spectrum decays with stretched exponential characterized by β < 1. In the diffusive case the fluorescence emission cannot be always fitted with double exponential, and the first moment of the emitted spectrum may decay with stretched exponential characterized by β > 1. Details of modeling and the possibilities of drawing conclusions are also presented.

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“…At the same time, Weber's & Spencer's (125) phase modulation technology was extended to the gigahertz region by Lakowitz & Gratton (57,58,(82)(83)(84)(85), who used the micro channel plate photo multiplier as a detector. These ultra-fast technologies led to many kinetic studies of fast reactions and to life-time studies of multi component fluoro chromes.…”

Section: Phase Modulationmentioning

confidence: 99%