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Use of high‐pressure freeze fixation and freeze fracture electron microscopy to study the influence of the phospholipid molar ratio in the morphology and alignment of bicelles
Author(s) -
BARBOSABARROS L.,
MAZA A. DE LA,
WALTHER P.,
LINARES A.M.,
FELIZ M.,
ESTELRICH J.,
LÓPEZ OLGA
Publication year - 2009
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.2008.03093.x
Subject(s) - lamellar structure , electron microscope , crystallography , chemistry , morphology (biology) , vesicle , electron micrographs , nuclear magnetic resonance , phospholipid , membrane , materials science , optics , biochemistry , physics , biology , genetics
Summary The high‐pressure freeze fixation and freeze fracture electron microscopy techniques were combined with the 31 P nuclear magnetic resonance to study the morphological transitions of two different dimyristoyl‐phosphatidilcholine/dihexanoyl‐phosphocholine aggregates by the effect of temperature. Through these techniques, the relationship between magnetic alignment and the morphology of alignable and non‐alignable aggregates was evaluated. The micrographs related to the non‐alignable dimyristoyl‐phosphatidilcholine/dihexanoyl‐phosphocholine sample presented rounded objects at a temperature below the dimyristoyl‐phosphatidilcholine phase transition (T m ) and, above this temperature an increase of viscosity was followed by the appearance of large elongated aggregates. The micrographs related to the alignable dimyristoyl‐phosphatidilcholine/dihexanoyl‐phosphocholine sample presented discoidal objects below T m . Above T m , when the best alignment was achieved, the images showed large areas of lamellar stacked bilayers and the presence of some multilamellar vesicles. Our results reveal that the composition of the aggregates is a key factor determining the morphological transitions of the bicellar systems. Understanding of the rules governing these transitions is crucial to modulate characteristics of these systems and to adequate them for different applications.