Determination of the mechanical properties of DOPC:DOPS liposomes using an image procession algorithm and micropipette-aspiration techniques

Rodowicz, Kathleen Allen; Francisco, Herbert; Layton, Bradley E.

doi:10.1016/j.chemphyslip.2010.09.004

Cited by 14 publications

(19 citation statements)

References 44 publications

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“…26 In our FE model, Young's modulus and Poisson's ration of the lipid bilayer are assumed to be 15 MPa and 0.5, respectively. 27 The Poisson's ratio of the RVE is also assumed to be 0.5.…”

Section: Methodsmentioning

confidence: 99%

The effect of local bending on gating of MscL using a representative volume element and finite element simulation

et al. 2014

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“…26 In our FE model, Young's modulus and Poisson's ration of the lipid bilayer are assumed to be 15 MPa and 0.5, respectively. 27 The Poisson's ratio of the RVE is also assumed to be 0.5.…”

Section: Methodsmentioning

confidence: 99%

The effect of local bending on gating of MscL using a representative volume element and finite element simulation

et al. 2014

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“…Surprisingly, these values increased with vesicle size, i.e., 14-20 μm. Elastic modulus is related to bending rigidity, k b , through k b = Et 3 =24, where t is the bilayer thickness (18,29,30). Therefore, the k b for small vesicles (diameter 5-8 μm) was 2.32 × 10 −20 J (Table 1).…”

Section: Significancementioning

confidence: 99%

“…This implies that when a local stress is produced in this area, the lipid membrane is unable to reconfigure itself and reduce the strain. Consequently, it restricts the movement of the elements (in FE simulation) and likely the phospholipids of the membrane (in reality) (18), thereby facilitating membrane rupture (Fig. S3).…”

Section: Significancementioning

confidence: 99%

“…These experiments have shown that the mechanical properties of lipids differ considerably and that lipid bilayers exhibit elastic behavior (14,15,18,19). The MA technique is versatile and has the advantage of exerting a wide range of aspiration pressures on a specific portion of a bilayer (20)(21)(22)(23).…”

mentioning

confidence: 99%

“…The mechanical properties of different types of lipids have been studied extensively using the micropipette aspiration (MA) approach (13)(14)(15)(16)(17)(18). These experiments have shown that the mechanical properties of lipids differ considerably and that lipid bilayers exhibit elastic behavior (14,15,18,19).…”

mentioning

confidence: 99%

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Biophysical implications of lipid bilayer rheometry for mechanosensitive channels

Bavi

Nakayama

Bavi

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The lipid bilayer plays a crucial role in gating of mechanosensitive (MS) channels. Hence it is imperative to elucidate the rheological properties of lipid membranes. Herein we introduce a framework to characterize the mechanical properties of lipid bilayers by combining micropipette aspiration (MA) with theoretical modeling. Our results reveal that excised liposome patch fluorometry is superior to traditional cell-attached MA for measuring the intrinsic mechanical properties of lipid bilayers. The computational results also indicate that unlike the uniform bilayer tension estimated by Laplace's law, bilayer tension is not uniform across the membrane patch area. Instead, the highest tension is seen at the apex of the patch and the lowest tension is encountered near the pipette wall. More importantly, there is only a negligible difference between the stress profiles of the outer and inner monolayers in the cellattached configuration, whereas a substantial difference (∼30%) is observed in the excised configuration. Our results have farreaching consequences for the biophysical studies of MS channels and ion channels in general, using the patch-clamp technique, and begin to unravel the difference in activity seen between MS channels in different experimental paradigms.MscL | azolectin | electrophysiology | finite element modeling L iposome reconstitution has been used for both functional and structural studies of bacterial mechanosensitive (MS) channels (MscL and MscS) for many years (1-4) and also more recently for the study of eukaryotic MS channels (5-8). Most frequently azolectin, a crude extract of phospholipids from animal and plant tissue consisting mainly of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (PI) (9), has been used for liposome preparations. Given the frequent use of azolectin bilayers for the study of MS channels and the importance of protein-lipid interactions in MS channel gating it is imperative to consider the best way to accurately calculate and assess its material properties. This is also essential for studies of voltage-and ligand-gated ion channels as the activity of these proteins can also be modulated by membrane tension (6-8, 10-12).The mechanical properties of different types of lipids have been studied extensively using the micropipette aspiration (MA) approach (13-18). These experiments have shown that the mechanical properties of lipids differ considerably and that lipid bilayers exhibit elastic behavior (14,15,18,19). The MA technique is versatile and has the advantage of exerting a wide range of aspiration pressures on a specific portion of a bilayer (20-23).Here we use this technique in combination with finite-element (FE) simulation to examine in depth the mechanical properties of azolectin bilayers in both cell-attached and excised patch configurations (SI Materials and Methods). It is widely known that lipid behavior is vastly different at low (<0.5 mN/m) compared with high tensions, due to thermal shape fluctuations (24). Given that the m...

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Cationic liposome/DNA complexes: from structure to interactions with cellular membranes

Caracciolo

Amenitsch

2012

Eur Biophys J

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Determination of the mechanical properties of DOPC:DOPS liposomes using an image procession algorithm and micropipette-aspiration techniques

Cited by 14 publications

References 44 publications

The effect of local bending on gating of MscL using a representative volume element and finite element simulation

The effect of local bending on gating of MscL using a representative volume element and finite element simulation

Biophysical implications of lipid bilayer rheometry for mechanosensitive channels

Cationic liposome/DNA complexes: from structure to interactions with cellular membranes

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