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Time-resolved fluorescence anisotropy for systems with lifetime and dynamic heterogeneity
R D Ludescher1, L Peting, S Hudson
1Department of Chemistry, University of Oregon, Eugene 97403.
Biophysical Chemistry
|October 1, 1987
Summary
Simulations show that fluorescence anisotropy decays reveal distinct fluorophore environments. Heterogeneous environments, not anisotropic rotor diffusion, explain specific decay patterns like rising anisotropy.
Area of Science:
- Photophysics
- Physical Chemistry
- Spectroscopy
Background:
- Fluorescence anisotropy decay is sensitive to molecular motion and environment.
- Understanding fluorophore behavior in complex systems is crucial for various applications.
Purpose of the Study:
- To illustrate the time dependence of fluorescence anisotropy for fluorophores in distinct environments.
- To analyze the interpretation of fluorescence anisotropy decays in terms of physical parameters.
Main Methods:
- Simulation calculations of fluorescence anisotropy decay.
- Analysis of simulated decays to identify underlying physical parameters.
- Evaluation of homogeneous environment models for heterogeneous behavior.
Main Results:
- Observed a wide range of fluorescence anisotropy decay behaviors.
- Demonstrated that specific decay features (high initial anisotropy, rising anisotropy, downward curvature) indicate heterogeneous environments.
- Showed that anisotropic rotor diffusion cannot explain these specific behaviors.
Conclusions:
- Heterogeneous environments are necessary to explain fluorescence anisotropy decays with high initial anisotropy and long-time rise.
- Downward curvature in anisotropy decays also suggests heterogeneous environments.
- Monotonically decreasing decays with positive second derivatives present ambiguities in interpreting motional behavior.