Energy‐filtered cryotransmission electron microscopy of liposomes prepared from human stratum corneum lipids

Abstract

We used cryo-TEM to examine the morphology of vesicles formed from lipids of the human stratum corneum (hSC). Human stratum corneum lipid liposomes (hSCLLs) were prepared in buffer at various pH values, using different preparation methods (film method, extrusion, ultrasonication, detergent dialysis). The morphology of hSCLLs at pH 7.4 differed markedly from that of liposomes formed by phospholipids, showing folds, stacks and membrane thickening. At pH 5.0, corresponding to natural conditions at the skin surface, membrane structures are essentially the same as those prepared at pH 7.4. Sharp edges in hSCLLs, branching membranes and stable membrane stacks were explained by the presence of ceramides, the major components and structural elements of human stratum corneum lipids (hSCLs). Thickened areas in the membranes may be caused by the local accumulation of triacylglycerols and cholesterol esters in the hydrophobic interior of the bilayer.

Vesicles with Hollow Rods in the Walls: A Trapped Intermediate Morphology in the Transition of Vesicles to Inverted Hexagonally Packed Rods in Dilute Solutions of PS-b-PEO

“…7 Thus, the present study may shed some light on the process of biomembrane fusion and the lipid lamella (L R ) to inverted hexagonal (H II ) phase transition. It is noteworthy that biomembrane thickening was reported recently, 8 although the study did not deal with the L R /H II transition, and the mechanism was thus very different. In conclusion, self-assembled vesicles with hollow rods running parallel to the surfaces of the walls have been prepared from PS-b-PEO diblocks in dilute solution.…”

“…Thus, the present study may shed some light on the process of biomembrane fusion and the lipid lamella (L α ) to inverted hexagonal (H II ) phase transition. It is noteworthy that biomembrane thickening was reported recently, although the study did not deal with the L α /H II transition, and the mechanism was thus very different.…”

Visualisation of liposomes prepared from skin and stratum corneum lipids by transmission electron microscopy

“…There are also present some drop like vesicles with sharp tips (s), hemispheres with one flattened part (h) and bag like liposomes with two hemispheres divided by a membrane (m). The morphology of this formulation is in accordance to the one prepared by Schmidtgen et al (1998) under the same conditions using human SC lipids.…”

“…1A(u)). Schmidtgen et al (1998) suggest that non-polar lipids like triacylglycerol may be positioned between the two monolayers of the lipid membrane, resulting in the thickening of the lipid bilayer. The presence of excessive amount of phospholipids may also lead to the formation of bag like vesicles, with two compartments separated by a common membrane (m).…”

Preparation and Characterization of Solid Lipid Nanoparticles of Cinnacalcet HCl

“…POL as non-ionic and SL as zwitterions surfactant resulted in electrostatic and steric stabilization of particles. Interpenetration of long polyethylene chains of poloxamer 407 limits freedom of the particles and prevents agglomeration [22]. Fig.…”