A new approach to polydispersity studies of sodium taurocholate and sodium taurodeoxycholate aggregates using dynamic fluorescence anisotropy
- Duke Univ., Durham, NC (United States)
Sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC) bile salt micelles in aqueous solution were investigated using perylene as a fluorescence anisotropy probe. By the introduction of a reduced correlation time in the anisotropy decay theory, it was possible to resolve the rotational correlation time of the smallest aggregate from these polydisperse systems. For both bile salts, comparison of the resolved correlation times with calculated values identified the smallest aggregate as the dimer. Temperature studies confirmed this result. The hydrodynamic radii of the bile salt dimers, calculated from the anisotropy results, were 7.2 [+-] 0.1 [angstrom] for NaTC and 7.3 [+-] 0.1 [angstrom] for NaTDC. The NaTC dimer as a percentage of all aggregates decreased from 68% to 56% at 20[degrees]C and from 82% to 67% at 40[degrees]C as the total monomer concentration of NaTC was increased from 20.0 to 100.0mM. For NaTDC at 20[degrees]C, a decrease from 43% to 35% was observed for the same increase in total concentration. The average aggregate size was found to be larger for NaTDC than NaTC. In the presence of 3.0 M NaCl, the percent dimer in NaTC solution remained relatively constant at approximately 33% as NaTC concentration was increased, although the average aggregate size increased. Addition of Tb[sup 3+] was found to significantly decrease the percent dimer in NaTC solution. A primary-secondary aggregation model is presented for a NaTC in which the primary miscellar unit is a dimer [open quotes]sandwich[close quotes] with perylene located between two bile salt monomers. The effects of dimer shape and the relationships between internal rotation of the probe and overall rotation of the probe-dimer complex on the experimental results are discussed. 41 refs., 3 figs., 7 tabs.
- DOE Contract Number:
- FG05-88ER13931
- OSTI ID:
- 6073320
- Journal Information:
- Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:25; ISSN JPCHAX; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ALKALI METAL COMPOUNDS
ANISOTROPY
AROMATICS
BILE ACIDS
CARBOXYLIC ACIDS
CHLORIDES
CHLORINE COMPOUNDS
CONDENSED AROMATICS
DATA
DIMERS
DISPERSIONS
EXPERIMENTAL DATA
FLUORESCENCE
HALIDES
HALOGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
LUMINESCENCE
MICELLAR SYSTEMS
MIXTURES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PERYLENE
SALTS
SODIUM CHLORIDES
SODIUM COMPOUNDS
SOLUTIONS
STEROIDS
STEROLS