Surface dilational behaviour of spread dipalmitoyl phosphatidyl glycerol monolayers

Wüstneck, R.; Enders, Peter; Wüstneck, N.; Pison, U.; Miller, R.; Vollhardt, D.

doi:10.1039/a906516d

Cited by 13 publications

(39 citation statements)

References 22 publications

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“…The injected volume was usually 0.2 l, varying at maximum between 0.1 and 0.4 l. Approximately the same volume was used by Wüstneck et al [3]. The lipid concentration was usually 0.2 mM.…”

Section: Lipid Depositionmentioning

confidence: 99%

“…The influence of oscillation amplitude was not studied systematically so far. Wüstneck et al [3] observe that the rheological parameters determined from harmonic oscillations may depend on the amplitude. Therefore, we present a systematic study of the influence of the oscillation amplitude and frequency on dilational elasticity and viscosity and the distortions caused by higher harmonics.…”

Section: Introductionmentioning

confidence: 99%

“…Consequences of surface rheology on respiratory performance have been discussed in detail [2][3][4][5]. Further, the surface rheology of phosAbbreviations: DPPC, dipalmitoylphosphatidylcholine; DPPG, dipalmitoylphosphatidylglycerol; DOPC, dioleoylphosphatidylcholine; ADSA, axisymmetric drop shape analysis; PAT, profile analysis tensiometer; THD, total harmonic distortion * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

“…Here, monolayer compression and expansion is more homogeneously distributed over the whole area than on a Langmuir trough. ADSA was used to study DPPC [4,21,30] and other phospholipid monolayers at the air-water interface [3,4,21,30,31], chloroform/water interface [21,22,30], n-dodecane/water interface [23,30] or dichloromethane/water interface [32]. Alternatively to a pendent drop, PAT can also be used to study a captive bubble under prescribed oscillations.…”

Section: Introductionmentioning

confidence: 99%

“…frequency and amplitude of harmonic area oscillations. Wüstneck et al [3] used PAT to study the stress relaxation process of a DPPG monolayer and the influence of oscillation frequency on the surface dilational viscosity and elasticity. The influence of oscillation amplitude was not studied systematically so far.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Surface rheology of monolayers of phospholipids and cholesterol measured with axisymmetric drop shape analysis

Vrânceanu

Winkler

Nirschl

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Surface rheology of monolayers of a saturated phospholipid (dipalmitoylphosphatidylcholine, DPPC), an unsaturated phospholipid (dioleoylphosphatidylcholine, DOPC) and cholesterol is studied with axisymmetric drop shape analysis at the argon/water interface. Measurement techniques for lipids are described in detail. Profile analysis tensiometry (PAT) is used to determine the film pressure Π, surface elasticity and surface dilational viscosity of monolayers upon sinusoidal oscillations of the drop surface for various amplitudes a and frequencies f to assess their dependence on these dynamic parameters. It is shown that surface dilational viscosity strongly depends on the frequency and decreases by a factor 2-5 with increasing f in the considered range. Dilational viscosity is higher the more the monolayer approaches a relaxed state. Thus, the molecular interactions are stronger in the relaxed than in the stressed state. Surface elasticity is much less dependent on dynamic conditions. For DPPC a minimum of the dynamic surface elasticity is found for f = 12.5 mHz (at Π = 17.5 mN m −1 ) which coincides well with the relaxation frequencies measured in stress relaxation experiments. The dynamic surface elasticity of DPPC exhibits a plateau in the range 13.5 mN m −1 ≤ Π ≤ 27 mN m −1 in good coincidence with the phase boundaries of the coexistence region of micron-sized liquid crystalline domains surrounded by a fluid monolayer phase. In equilibrium measurements (Π/A-isotherms) a plateau of the film pressure is seen at the lower bound and a break at the upper bound of the coexistence region. Film pressure/area isotherms produced by PAT and a Langmuir film balance closely coincide as is shown in a comparison to literature values. However, the surface elasticities measured dynamically with oscillating surfaces widely deviate from those derived from isotherms in the case of DPPC and cholesterol, whereas for DOPC very good agreement can be found.

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“…The injected volume was usually 0.2 l, varying at maximum between 0.1 and 0.4 l. Approximately the same volume was used by Wüstneck et al [3]. The lipid concentration was usually 0.2 mM.…”

Section: Lipid Depositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Surface rheology of monolayers of phospholipids and cholesterol measured with axisymmetric drop shape analysis

Vrânceanu

Winkler

Nirschl

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

View full text Add to dashboard Cite

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Design and accuracy of pendant drop methods for surface tension measurement

Saad

Policova

Neumann

2011

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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pH-Induced Changes in the Surface Viscosity of Unsaturated Phospholipids Monitored Using Active Interfacial Microrheology

Ghazvini¹,

Alonso²,

Alhakamy

et al. 2017

Langmuir

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Lipid membranes, a major component of cells, are subjected to significant changes in pH depending on their location in the cell: the outer leaflet of the cell membrane is exposed to a pH of 7.4 whereas lipid membranes that make up late endosomes and lysosomes are exposed to a pH of as low as 4.4. The purpose of this study is to evaluate how changes in the environmental pH within cells alter the fluidity of phospholipid membranes. Specifically, we studied pH-induced alterations in the surface arrangement of monounsaturated lipids with zwitterionic headgroups (phosphoethanolamine (PE) and phosphocholine (PC)) that are abundant in plasma membranes as well as anionic lipids (phosphatidylserine (PS) and phosphatidylglycerol (PG)) that are abundant in inner membranes using a combination of techniques including surface tension vs area measurements, interfacial microrheology, and fluorescence/atomic force microscopy. Using an active interfacial microrheology technique, we find that phospholipids with zwitterionic headgroups show a significant increase in their surface viscosity at acidic pH. This increase in surface viscosity is also found to depend on the size of the lipid headgroup, with a smaller headgroup showing a greater increase in viscosity. The observed pH-induced increase in viscosity is also accompanied by an increase in the cohesion pressure between zwitterionic molecules at acidic pH and a decrease in the average molecular area of the lipids, as measured by fitting the surface pressure isotherms to well-established equations of state. Because fluorescent images show no change in the phase of the lipids, we attribute this change in surface viscosity to the pH-induced reorientation of the P-N dipoles that form part of the polar lipid headgroup, resulting in increased lipid-lipid interactions. Anionic PG headgroups do not demonstrate this pH-induced change in viscosity, suggesting that the presence of a net negative charge on the headgroup causes electrostatic repulsion between the headgroups. Our results also show that active interfacial microrheology is a sensitive technique for detecting minute changes in the lipid headgroup orientation induced by changes in the local membrane environment, even in unsaturated phospholipids where the surface viscosity is close to the experimental detection limit.

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Surface dilational behaviour of spread dipalmitoyl phosphatidyl glycerol monolayers

Cited by 13 publications

References 22 publications

Surface rheology of monolayers of phospholipids and cholesterol measured with axisymmetric drop shape analysis

Surface rheology of monolayers of phospholipids and cholesterol measured with axisymmetric drop shape analysis

Design and accuracy of pendant drop methods for surface tension measurement

pH-Induced Changes in the Surface Viscosity of Unsaturated Phospholipids Monitored Using Active Interfacial Microrheology

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