Stearic acid monolayers on heavy water

Dreher, K.D.; Sears, D. F.

doi:10.1039/tf9666200741

Cited by 30 publications

(4 citation statements)

References 2 publications

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“…A comparison of stearic acid monolayers on H20 and D20 (26) found identical isotherms in both situations in the condensed states whereas a pressure reduction on the D20 subphase was reported at low pressures, qualitatively similar to our observation. The surface normal projected dipole moment per lipid molecule at the interface was reported to be increased by 5% on the D20 subphase (26). As in the case of the chain deuteration, vesicle dispersions show water deuteration-dependent shifts in their phase transition temperatures (27, 28) that are qualitatively consistent with our findings although this effect is about five times larger with the monolayer experiments.…”

Section: Discussionsupporting

confidence: 90%

Structural properties of phosphatidylcholine in a monolayer at the air/water interface

Vaknin¹,

Kjær²,

Als‐Nielsen³

et al. 1991

Biophysical Journal

185

126

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Neutron reflectivities of phosphatidylcholine monolayers in the liquid condensed (LC) phase on ultrapure H(2)O and D(2)O subphases have been measured on a Langmuir film balance. Using a dedicated liquid surface reflectometer, reflectivities down to R = 10(-6) in the momentum transfer range Q(z) = 0-0.4 A(-1) were accessed.In a new approach, by refining neutron reflectivity data from chain-perdeuterated DPPC-d(62) in combination with x-ray measurements on the same monolayer under similar conditions it is shown that the two techniques mutually complement one another. This analysis leads to a detailed conception of the interface structure. It is found that in the LC phase (which is analogous to the L(beta), phase in vesicle dispersions) the head group is interpenetrated with subphase water (4 +/- 2.5 molecules per lipid) and the average tilt angle of the hydrophobic chains from the surface normal is 33 +/- 3 degrees.

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Section: Discussionsupporting

confidence: 90%

Structural properties of phosphatidylcholine in a monolayer at the air/water interface

Vaknin¹,

Kjær²,

Als‐Nielsen³

et al. 1991

Biophysical Journal

185

126

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“…No tilted polydomain structures are found in 12-HSA, while they are observed in stearic acid, its non-hydroxylated counterpart . According to the data of surface dipole moments, the surface dipole moment in the condensed phase is comparable with the values reported for stearic acid monolayers, which further suggests that molecules have a vertical orientation after the intermediate plateau region.…”

Section: Resultssupporting

confidence: 65%

Surface Rheological Transitions in Langmuir Monolayers of Bi-Competitive Fatty Acids

2002

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This paper discusses a rheological and structural transition that is observed for Langmuir films of 12-hydroxystearic acid. This molecule presents an interesting bi-competitive absorption between primary and secondary hydrophilic groups on either end of an alkane chain, which leads to a sharp transition from an expanded phase to a crystalline condensed morphology as surface pressure is increased. This abrupt morphological transition is accompanied by a strong change in the interfacial rheology of the films. These observations are obtained using an instrument that allows the acquisition of Brewster angle microscopy (BAM) simultaneously with the measurement of dynamic interfacial moduli. Below the transition, it is demonstrated that the films are purely viscous and characterized by a Newtonian rheology. However, above a transition pressure, the films behave as solidlike and crystalline with high elasticity. It is argued that the transition occurs through an evolution from a flat molecular configuration on the surface with both hydrophilic ends adsorbed at the water interface to a vertical, straightened state that has the secondary hydrophilic group lifted out of the subphase. The crystalline phase is highly non-Newtonian with a frequency-dependent dynamic surface viscosity.

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“…Furthermore, the surface potentials and surface viscosity of stearic acid monolayers are altered when water is replaced by heavy water in the substrate for the monolayer [20]. These experiments indicate that the molecular arrangement of monolayer molecules is in part determined by the interaction of the monolayer with the substrate.…”

Section: Discussionmentioning

confidence: 87%

“…The surface viscosities of the monolayers were determined by the canal method which has been described previously [18][19][20]. The surface area of the monolayer was reduced to produce the desired surface pressure using a Teflon barrier which contained a transverse slit, 0.15 cm wide and 2.5 cm long.…”

Section: Methodsmentioning

confidence: 99%

Effects of phenothiazines on the surface pressures, potentials and viscosities of monolayers of lecithin and/or cholesterol1

Sears

Brandes

1969

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The effects of four phenothiazines at 10 -a M concentration on monolayers of lecithin, cholesterol and mixed monolayers of lecithin and cholesterol were examined using surface chemical techniques. These phenothiazines produced expansion of the area per monolayer molecule at low surface pressure, facilitated the disruption of the monolayers from the water substrate at high surface pressures, increased the surface viscosity of the monolayers, and decreased the surface potentials. The data suggest that the site of action of these agents is immediately beneath the monolayers.

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Stearic acid monolayers on heavy water

Cited by 30 publications

References 2 publications

Structural properties of phosphatidylcholine in a monolayer at the air/water interface

Structural properties of phosphatidylcholine in a monolayer at the air/water interface

Surface Rheological Transitions in Langmuir Monolayers of Bi-Competitive Fatty Acids

Effects of phenothiazines on the surface pressures, potentials and viscosities of monolayers of lecithin and/or cholesterol1

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