Monomeric and aggregated pyrene and 16-(1-pyrenyl)hexadecanoic acid in small, unilamellar phosphatidylcholine vesicles and ethanol—buffer solutions

Lysozyme effect on structural state of model membranes as revealed by pyrene excimerization studies

“…Taking K D =2.8 M À1 , C PL =0.016 M, c D was found to be about 4% of C PL , suggesting that contribution of static excimers to the total fluorescence is insignificant. In this regard, it is also noteworthy that no ground-state dimers or other molecular aggregates were detected with up to 4 mol% of pyrene incorporated into PC liposomes [30]. Based on the above reasoning, we considered pyrene excimerization in the model membranes under study as a diffusion-controlled process.…”

“…Pyrene dimerization in PC/CL membranes seems to be hardly probable for the following reasons. Firstly, dimer formation should manifest itself in a strong hypochromism and decrease of monomer fluorescence [23,30]. However, in the absence of lysozyme, no marked changes in the pyrene fluorescence intensity were observed on increasing CL content from 0 to 40 mol% (Fig.…”

Study of Singlet Oxygen Equilibrium in Dioctadecyldimethylammonium Chloride Vesicles Employing 2-(n-(N,N,N-trimethylamine)-n-alkyl)- 5-alkylfuryl Halides†

“…For DODAC vesicles, MB permeation through the bilayer is negligible at room temperature (20 ± 2°C) (39). In addition, we consider that DFTA and HFDA should be located exclusively in the lipidic pseudophase, because of the structural similarity with anthracene and pyrene derivatives currently employed as fluorescent probes in vesicles of synthetic and natural surfactants (40–44). The trimethylammonium head and the length of the tether alkyl group locate the reactive furan moiety at different depths in the vesicle bilayer.…”

Reactions in lipid vesicles. Pyrene excimer formation in restricted geometries. Effect of temperature and concentration

“…Pyrene has been previously used to probe the structure and dynamics of phospholipid vesicles (see Daems et al 1985;L'Heureux and Fragata 1989). The analysis of the fluorescence decay profiles of pyrene, which is also the main topic of the present work, has been done either by fitting a sum of exponentials (Liu et al 1980) or by utilizing a time-dependent diffusion coefficient based on the Einstein-Smoluchowski diffusion theory (Vanderkooi and Callis 1974).…”

“…The analysis of the fluorescence decay profiles of pyrene, which is also the main topic of the present work, has been done either by fitting a sum of exponentials (Liu et al 1980) or by utilizing a time-dependent diffusion coefficient based on the Einstein-Smoluchowski diffusion theory (Vanderkooi and Callis 1974). A controversy has arisen as to which of the two models might be appropriate, since diffusion-controlled excimer formation of pyrene in phospholipid vesicles is in some cases questioned (Blackwell et al 1986;L'Heureux and Fragata 1989). The present work sheds some light on this question while it introduces the concept of dimensionality into the employed mathematical models.…”