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- Dimitrievski, Kristian, 1974
(författare)
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Deformation of adsorbed lipid vesicles as a function of vesicle size
- 2010
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 26:5, s. 3008-3011
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Tidskriftsartikel (refereegranskat)abstract
- Experimental indications that adsorbed lipid vesicles arc deformed on the surface (e.g., oil SiO(2)) and that the deformation seems to be more pronounced for larger vesicles have been reported. In general. it has been assumed that larger vesicles should,how a stronger tendency for spontaneous rupture, which is also backed up by thermodynamic considerations (Seifert, U.; Lipowsky, R. PhYs. Rev. A 1990,42,4768; Seifert, U. Adv. PhYs. 1997, 46, 13). However, using a newly developed model of a lipid bilayer, simulations were performed to study the shape of adsorbed lipid vesicles for different vesicle sizes, with the observation that larger vesicles indeed are more deformed on the surface, but that there is no additional tendency for larger vesicles to rupture spontaneously. It is shown here that the radius of curvature, on the portions of the vesicle membrane that are most strained. is practically independent of the vesicle size. A kinetic barrier for vesicle rupture is proposed to be the reason for the observed disagreement with thermodynamic theory.
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| 2. |
- Dimitrievski, Kristian, 1974
(författare)
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Influence of lipid-bilayer-associated molecules on lipid-vesicle adsorption
- 2010
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 26:8, s. 5706-5714
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Tidskriftsartikel (refereegranskat)abstract
- Supported lipid bilayers (SLBs) containing, different types of bilayer-associated molecules (membrane-hound molecules) where one part of the molecule resides inside the lipid bilayer and another part of the molecule sticks out of the hi layer (e.g.. membrane proteins) are important biophysical model systems. SLBs are commonly formed via lipid vesicle adsorption on certain surfaces (e.g., SiO(2)). However, vesicles doped with different types of (bio)molecules often do not form an SLII on the surface, and the reasons for this are not clear. Using a newly developed model of a lipid bilayer, simulations were performed to clarify the influence of the bilayer-associated molecules on vesicle adsorption and rupture. It is shown that by increasing the concentration of membrane-bound molecules in the vesicles the tendency for vesicle rupture decreases markedly and for a certain concentration rupture does not happen. The reason for this is that vesicles containing significant concentrations of such molecules tend to deform less on the surface (lower vesicle strain), especially for a significantly corrugated bilayer surface potential. After vesicle rupture, membrane-bound molecules face either the surface or the solution in the resulting bilayer patch on the surface, depending on whether the molecules point outward or inward in the original vesicle, respectively. Vesicle surface diffusion is also studied for weak and strong surface corrugation; where vesicles are found to be almost immobile in the latter case.
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| 3. |
- Dimitrievski, Kristian, 1974, et al.
(författare)
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Simulations of lipid transfer between a supported lipid bilayer and adsorbing vesicles
- 2010
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 75:2, s. 454-465
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Tidskriftsartikel (refereegranskat)abstract
- Recent experiments demonstrate transfer of lipid molecules between a charged, supported lipid membrane (SLB) and vesicles of opposite charge when the latter adsorb on the SLB. A simple phenomenological bead model has been developed to simulate this process. Beads were defined to be of three types, 'n', 'p', and '0', representing POPS (negatively charged), POEPC (positively charged), and POPC (neutral but zwitterionic) lipids, respectively. Phenomenological bead-bead interaction potentials and lipid transfer rate constants were used to account for the overall interaction and transfer kinetics. Using different bead mixtures in both the adsorbing vesicle and in the SLB (representing differently composed/charged vesicles and SLBs as in the reported experiments), we clarify under which circumstances a vesicle adsorbs to the SLB, and whether it, after lipid transfer and changed composition of the SLB and vesicle, desorbs back to the bulk again or not. With this model we can reproduce and provide a conceptual picture for the experimental findings
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