Rotational diffusion of coumarin laser dye studied by fluorescence depolarization technique

2006 ◽  
Vol 56 (S4) ◽  
pp. D533-D538
U. S. Raikar ◽  
C. G. Renuka ◽  
M. S. Raikar
1977 ◽  
V. Hofmann ◽  
P.W. Straub ◽  
T. Binkert ◽  
E. Serrallach ◽  
W. Känzig ◽  

In order to obtain information on size and shape of the fibrinogen molecule in solution the translational diffusion coefficient (DT), the rotational diffusion coefficients (DR⊥ and DR//) and the sedimentation coefficients (S) have been measured on human fibrinogen with a clottaoility above 95%. The methods used were dynamic light scattering, nanosecond fluorescence depolarization and analytical ultracentrifugation. Dynamic light scattering yields DT = 2.0 ± 3% x 10-7 cm2sec–1 at a concentration of 7 mg/ml in 0.15 M Tris-NaCl, pH 7.4. DT is strongly dependent on concentration, being 3.4 ± 10% × 10-7 cm2 sec-1 at 0.1 mg/ml. The rotation along the minor axis as measured with the same method is DR = // 1.5 × 106 sec-1 at 0.1 mg/ml. The rotation along the major axis as measured on fibrinogen labeled with dansylchloride is DR// = 1.5 x106 sec–1. S is also strongly dependent on concentration, being 7.9 S at 0.1 mg/ml, 8.1 S at 1 mg/ml and 6.6 S at 10 mg/ml.These results fit with an elongated molecule having an axial ratio of 7. They are compatible with a MW of 340’000 only for concentrations above 2 mg/ml, while at lower concentrations (0.1 mg/ml) they agree with a MW of approximately half the accepted value.

1993 ◽  
Vol 58 (2) ◽  
pp. 213-233 ◽  
Zuzana Limpouchová ◽  
Karel Procházka ◽  
Vlastimil Fidler ◽  
Jiří Dvořák ◽  
Bohumil Bednář

Theories allowing interpretation of the results of time-resolved polarization spectrofluorimetry in solutions are reviewed and their applicability under various conditions is discussed. For the reorientation of rigid molecules in an isotropic medium, the most frequently employed models are presented, such as rotational diffusion model, the Fokker-Planck-Langevin model, etc. Systems with internal rotation, systems in anisotropic media, systems with a complex electron relaxation and systems with energy transfer are discussed as examples of more complex systems. A special attention is devoted to the polarization fluorimetry of probes bound to/or sorbed at polymer and biopolymer chains. The review focuses on theoretical models of reorientational motion for interpretation of fluorescence anisotropy decays. Experimental studies and computer simulations are discussed only when it is necessary for comparison with theoretical predictions. Complicated models for simultaneous reorientational motion and energy transfer, solvent relaxation, etc., although very important for many applications, exceed the scope of this review and are mentioned only very briefly.

2015 ◽  
Vol 93 (1) ◽  
pp. 3-6 ◽  
Y.F. Nadaf ◽  
C.G. Renuka

Rotational diffusion analysis of two laser dyes, coumarin 6 and coumarin 30, has been studied in alkane and alcohol solvents using steady-state and time-resolved fluorescence depolarization methods. The rotational diffusion times of these probes vary linearly as a function of viscosity over the range of temperature studied. It is observed that the rotational diffusion time measurements of molecules in alcohol and alkane have relaxation times typically on the order of picoseconds, though they are greater in alcohol than in alkane solvents. However, it was observed that coumarins rotate faster in n-hexane and n-heptane than in n-propanol and n-butanol solvents, and the observed results are discussed in the last section.

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