An electron spin resonance study of the soy bean phosphatidylcholine-based reversed micelles

Abstract

The ESR spectra of I-palmitoyl-2-stearoyl-(n-doxyl)-glycero-3-phosphocholine spin label positional isomers (n = 5, 7, 10, 12 and 16) have been studied in soy bean phosphatidylcholine (SPC)-based microemulsions with various volume fractions of disperse phase over the wide temperature range. The maximum hyperfine splitting 2A... and the order parameters S were taken as indices of the rotational mobility and the motion spatial restrictions of the labeled lipid chain segments. It is found that the temperatures T,, at which sharp enhancements of 2A n, ax and S occur depend on concentration and size of the reversed micelles in solutions. To explain this, a plausible model, taking into account capability of the SPC molecule hydrocarbon chains to change a tilt angle with respect to the surface of a polar head group as temperature varies, is proposed. The estimations of the correlation times si obtained from the lineshape characteristics of the ESR spectra provided the possibility to suggest that these correlation times characterize the reorientations of the SPC chain axis about the normal to the surface of a polar head group of a reversed micelle.

Bioinspired Nanoemulsions Stabilized by Phosphoethanolamine and Phosphoglycerol Lipids

“…PLs vesicles, prepared with a well-established method (see Section 2.4 ), were chosen as a reference system. Indeed, while EPR is a well-consolidated approach to characterize lipid bilayers [ 37 ], it has been only seldom used for PLs reverse micelles [ 38 ]. To the best of our knowledge this is the first time that the same method is used for lipid monolayers stabilizing emulsion droplets.…”

Effects of protein solubilization on the structure of the surfactant shell of reverse micelles

“…The use of amphiphilic spin probes, which are incorporated into the surfactant interface, can gire an important information on surfactant packing, local mobility of its molecules, micropolarity in different domains of the surfactant layer [17][18][19][20] thus helping to answer what happens with the surfactant shell structure under the influence of the solubilized protein molecule.…”

The influence of sodium salicylate on the micellar rate effect and the structural behaviour of dodecylpyridinium bromide micelles

“…12 The X-band EPR spectra were recorded on an RE 1306 spectrometer under conditions described elsewhere. 13 5-Doxyl-stearic acid (Sigma) was used as a spin label in a concentration of 5×10 -4 mol dm -3 . The reaction was monitored by observing the p-nitrophenolate anion absorption using a 'Specord M-400' spectrophotometer equipped with temperature-controlled cell holders.…”