arXiv subjects

M. Hishida

Publications and source records attributed to M. Hishida.

3 recordsLinked to original sources

arXiv2006

Unbinding Transition Induced by Osmotic Pressure in Relation to Unilamellar Vesicle Formation

Small-angle X-ray scattering and phase-contrast microscopy experiments were performed to investigate the effect of the osmotic pressure on vesicle formation in a dioleoylphosphatidylcholine (DOPC)/water/NaI system. Multi-lamellar vesicles were formed when a pure lipid film was hydrated with an aqueous solution of NaI. On the other hand, uni-lamellar vesicles (ULVs) were formed when a lipid film mixed with an enough amount of NaI was hydrated. To confirm the effect of the osmotic pressure due to NaI, a free-energy calculation was performed. This result showed that the osmotic pressure induced an unbinding transition on the hydration process, which resulted in ULV formation.

cond-mat.soft↗

arXiv2006

Hydration process of multi-stacked phospholipid bilayers to form giant vesicles

The hydration process of multi-stacked phospholipid bilayers to form giant vesicles was investigated by time-resolved small angle X-ray scattering. The hydration of lipids in the liquid-crystalline phase was found to proceed in two stages. In the early stage, until about 100 s after hydration, lipid bilayers on a solid substrate swell about 12 $\rmÅ$ and reach a quasi-stable state. In the late stage, after several hundreds of seconds, lipid bilayers gradually peel off from the stack. On the other hand, in the case of a lipid in the gel phase, only the early stage is observed. These behaviors correspond to the capacity for the giant vesicle formation depending on the lipid phases. The kinetics of the peeling-off process is discussed in terms of Kramers' formulas.

physics.chem-ph↗

arXiv2006

A swollen phase observed between the liquid-crystalline phase and the interdigitated phase induced by pressure and/or adding ethanol in DPPC aqueous solution

A swollen phase, in which the mean repeat distance of lipid bilayers is larger than the other phases, is found between the liquid-crystalline phase and the interdigitated gel phase in DPPC aqueous solution. Temperature, pressure and ethanol concentration dependences of the structure were investigated by small-angle neutron scattering, and a bending rigidity of lipid bilayers was by neutron spin echo. The nature of the swollen phase is similar to the anomalous swelling reported previously. However, the temperature dependence of the mean repeat distance and the bending rigidity of lipid bilayers are different. This phase could be a precursor to the interdigitated gel phase induced by pressure and/or adding ethanol.

cond-mat.soft↗