Characterization of a fluorescence assay to monitor changes in the aqueous volume of lipid vesicles

✍ Scribed by Debra A. Kendall; Robert C. MacDonald

• Book ID: 102986917
• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 603 KB
• Volume: 134
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(83)90258-0

✦ Synopsis

The fluorescent compound, 4',5'-bis[N,N-bis(carboxymethyl)aminomethyl] fluorescein (calcein) has been characterized for use in lipid vesicle studies. Particularly useful is its reaction with Co2+, which results in fluorescence quenching. This is accompanied by about a 10-nm blue shift in the uv absorbance bands and a small reduction in the visible absorbance band. For vesicle studies, Co2+ may be combined with citrate, which does not significantly hinder calcein quenching by Co2+. It does augment the absorbance of the metal ion. No significant interaction of citrate X Co2+ with phosphatidylserine vesicles was observed. Zn2+ is capable of displacing Co2+ and restoring calcein fluorescence. Fluorescence quenching due to formation of the calcein X Co2+ complex can also be reversed with EDTA. Thus, calcein is the basis of some simple reactions which can be used to assay changes in the aqueous volume of lipid vesicles.