Donor-donor energy migration (DDEM) as a tool for studying aggregation in lipid phases
2001 (English)In: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR, ISSN 1386-1425, Vol. 57, no 9, 1839-45 p.Article in journal (Refereed) Published
A BODIPY(R)-labelled sulfatide (N-(BODIPY(R)- FL-pentanoyl) -galactosylcerebroside-sulfate, hereafter abbreviated as BD-Sulfatide) was solubilised at different concentrations in lipid vesicles of 1,2-dioleoyl-sn -glycero-3-phosphocholine (DOPC). Time-correlated single photon counting experiments show that the fluorescence relaxation is mono-exponential (with a lifetime of 6.5 ns) at molar ratios of BD-Sulfatide: DOPC that are less than 1:100. The fluorescence steady-state anisotropy decreases monotonously at molar ratios smaller than 1:1000, which is compatible with donor-donor energy migration (DDEM) among the BODIPY(R) groups. A model that assumes DDEM across the lipid bilayers, as well as in their planes, was used to analyse the time-resolved fluorescence anisotropy. Only two parameters appear in the model namely; the bilayer thickness (d) and the average number density (C-2) distribution of BD-Sulfatide in the lipid bilayers. The extracted d-values vary between 35 and 40 Angstrom, which is about the reported thickness of a bilayer of DOPC (38 Angstrom). Hence, the BODIPY(R) groups are preferentially located in the water-lipid interface. At low concentration the experimental C-2-values and those independently calculated are in good agreement, while the experimental values gradually become lower with increasing BD-Sulfatide concentration. These results are compatible with an aggregation of the sulfatides and self-quenching of BODIPY(R), which is clearly established at higher concentrations of the BD-Sulfatide.
Place, publisher, year, edition, pages
2001. Vol. 57, no 9, 1839-45 p.
IdentifiersURN: urn:nbn:se:umu:diva-8649DOI: doi:10.1016/S1386-1425(01)00411-5OAI: oai:DiVA.org:umu-8649DiVA: diva2:148320