Increase of Fluorescence Anisotropy Upon Self-Assembly in Headgroup-Labeled Surfactants

✍ Scribed by Mark Kastantin; Badriprasad Ananthanarayanan; Brian Lin; Jan Ressl; Matthew Black; Matthew Tirrell

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 153 KB
• Volume: 7
• Category: Article
• ISSN: 1616-5187
• DOI: 10.1002/mabi.200600203

✦ Synopsis

Abstract

The change in fluorescence anisotropy upon micellization in headgroup‐labeled surfactants is investigated. After eliminating the likelihood of depolarizing RET, anisotropy is shown to increase upon self‐assembly due to increased rotational correlation times of the fluorophore. This is shown using two surfactant‐fluorophore systems. Anisotropy in NBD‐labeled phospholipids is studied both in chloroform (unaggregated) and in water (unilamellar vesicles), while in tryptophan‐containing peptide‐amphiphiles, the variation of anisotropy with concentration leads to a reasonable measurement of CAC. Anisotropy increase is shown to be largely the product of increased rotational correlation times for the fluorophore, relative to its τ. These results serve as a basis for future work that measures the amount of depolarizing energy transfer, characterizing distances between similar fluorescent headgroups on mixed micelles.

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