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Gold nanoparticles quench fluorescence by phase induced radiative rate suppression
E Dulkeith1, M Ringler, T A Klar
1Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universität München, Germany.
Nano Letters
|April 14, 2005
Summary
Researchers studied how the distance between Cy5 molecules and gold nanoparticles affects fluorescence. The study found that the radiative decay rate, not the non-radiative rate, primarily controls the distance-dependent quantum efficiency.
Area of Science:
- Nanotechnology
- Photochemistry
- Spectroscopy
Background:
- Gold nanoparticles exhibit unique optical properties.
- Fluorescent molecules like Cy5 are widely used in bioimaging.
- The interaction between nanoparticles and fluorophores influences photophysical properties.
Purpose of the Study:
- To investigate the effect of distance on the fluorescence quantum yield of Cy5.
- To determine the contributions of radiative and non-radiative decay rates to quantum yield.
- To understand the role of single-stranded DNA (ssDNA) spacers in modulating these interactions.
Main Methods:
- Utilized gold nanoparticles functionalized with varying lengths of ssDNA.
- Attached Cy5 fluorescent dyes to the ssDNA spacers.
- Employed time-resolved photoluminescence spectroscopy to measure decay rates.
- Analyzed fluorescence quantum yield as a function of Cy5-nanoparticle distance (2-16 nm).
Main Results:
- Observed a distance-dependent change in fluorescence quantum yield.
- Found that the radiative decay rate is the dominant factor controlling quantum efficiency.
- Non-radiative decay rates showed minimal influence on the observed distance dependence.
Conclusions:
- The radiative decay rate of Cy5 is highly sensitive to its proximity to gold nanoparticles.
- ssDNA length is an effective tool for tuning the optical properties of nanoparticle-dye systems.
- Understanding these distance-dependent effects is crucial for designing advanced optical nanosensors and imaging agents.