The evaporation resistances of octadecanol-cholesterol mixed monolayers

Barnes, G.T; Bacon, K.J; Ash, Jillian

doi:10.1016/0021-9797(80)90295-7

Cited by 14 publications

(5 citation statements)

References 16 publications

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“…For example, the insertion of lipase into SSA surfaces could increase particle hygroscopicity due to the disordering of the lipids at the interface, evidenced by the decrease in nematic order parameter and the increase in monolayer curvature. Tight-packing conformations of lipids in a monolayer film have previously been cited as a barrier to water uptake. ,,, Early studies on mixed lipid monolayer films show a well-characterized drop in monolayer resistance in the presence of low concentrations of impurities. − At high surface pressures with highly aligned lipid-packing conformations, it can be expected that a small defect such as a disruption to the monolayer microstructure by lipase will lead to a large drop in monolayer resistance and a corresponding increase in water permeation across the interface. Because of this, it may be reasonable to suspect that lipase-containing SSA could account for a portion of the cloud condensation nucleation activity of organic-enriched aerosols.…”

Section: Resultsmentioning

confidence: 99%

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces

et al. 2019

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Lipases, as well as other enzymes, are present and active within the sea surface microlayer (SSML). Upon bubble bursting, lipases partition into sea spray aerosol (SSA) along with surface-active molecules such as lipids. Lipases are likely to be embedded in the lipid monolayer at the SSA surface and thus have the potential to influence SSA interfacial structure and chemistry. Elucidating the structure of the lipid monolayer at SSA interfaces and how this structure is altered upon interaction with a protein system like lipase is of interest, given the importance of how aerosols interact with sunlight, influence cloud formation, and provide surfaces for chemical reactions. Herein, we report an integrated experimental and computational study of Burkholderia cepacia lipase (BCL) embedded in a lipid monolayer and highlight the important role of electrostatic, rather than hydrophobic, interactions as a driver for monolayer stability. Specifically, we combine Langmuir film experiments and molecular dynamics (MD) simulations to examine the detailed interactions between the zwitterionic dipalmitoylphosphatidylcholine (DPPC) monolayer and BCL. Upon insertion of BCL from the underlying subphase into the lipid monolayer, it is shown that BCL permeates and largely disorders the monolayer while strongly interacting with zwitterionic DPPC molecules, as experimentally observed by Langmuir adsorption curves and infrared reflectance absorbance spectroscopy. Explicitly solvated, all-atom MD is then used to provide insights into inter- and intramolecular interactions that drive these observations, with specific attention to the formation of salt bridges or ionic-bonding interactions. We show that after insertion into the DPPC monolayer, lipase is maintained at high surface pressures and in large BCL concentrations by forming a salt-bridge-stabilized lipase–DPPC complex. In comparison, when embedded in an anionic monolayer at low surface pressures, BCL preferentially forms intramolecular salt bridges, reducing its total favorable interactions with the surfactant and partitioning out of the monolayer shortly after injection. Overall, this study shows that the structure and dynamics of lipase-embedded SSA surfaces vary based on surface charge and pressure and that these variations have the potential to differentially modulate the properties of marine aerosols.

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Section: Resultsmentioning

confidence: 99%

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces

et al. 2019

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“…Related to this discussion, several researchers have investigated the evaporation of water coated with 2-component organic monolayers. 55,77,[84][85][86][87][88][89][90] Researchers have generally found that the resistance to water evaporation due to an ideal, miscible monolayer can be explained with eq 6. 77,90 For immiscible monolayers, none of the water evaporation studies could be explained by eq 5 (or eq 6).…”

Section: Resultsmentioning

confidence: 99%

“…77,90 For immiscible monolayers, none of the water evaporation studies could be explained by eq 5 (or eq 6). 48,56,85,87,89 For example, several studies have investigated the evaporation resistance of 1-octadecanol-cholesterol monolayers (which are expected to be immiscible) and have shown resistances that are appreciably lower than those predicted by eq 5. 85,89 For example, deviations from model predictions by up to a factor of 2.2 were observed by Barnes et al 85 Possible explanations for why evaporation resistance measurements through immiscible monolayers are not a The average molecular surface areas for each 2-component monolayer (determined from the pressure-area isotherms) are also included.…”

Section: Resultsmentioning

confidence: 99%

“…Related to this discussion, several researchers have investigated the evaporation of water coated with 2-component organic monolayers. ,,– Researchers have generally found that the resistance to water evaporation due to an ideal, miscible monolayer can be explained with eq . , For immiscible monolayers, none of the water evaporation studies could be explained by eq (or eq ). ,,,, For example, several studies have investigated the evaporation resistance of 1-octadecanol−cholesterol monolayers (which are expected to be immiscible) and have shown resistances that are appreciably lower than those predicted by eq . , For example, deviations from model predictions by up to a factor of 2.2 were observed by Barnes et al Possible explanations for why evaporation resistance measurements through immiscible monolayers are not consistent with eq include partial miscibility or mass transfer occurring mainly at grain boundaries …”

Section: Resultsmentioning

confidence: 99%

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Reactive Uptake of N₂O₅on Aqueous H₂SO₄Solutions Coated with 1-Component and 2-Component Monolayers

Cosman

Bertram

2008

J. Phys. Chem. A

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Reactive uptake of N(2)O(5) on aqueous sulfuric acid solutions was studied in the presence of 1-component (octadecanol) and 2-component (octadecanol + phytanic acid) monolayers. In the 1-component monolayer experiments, the reactive uptake coefficient depended strongly on the molecular surface area of the surfactant. Also, the 1-component monolayer showed significant resistance to mass transfer even when the fractional surface coverage of the surfactant was less than 1. For example, a monolayer of 1-octadecanol with a fractional surface coverage of 0.75 decreased the reactive uptake coefficient by a factor of 10. This is consistent with previous studies. In the 2-component monolayer experiments, the reactive uptake coefficient depended strongly on the composition of the monolayer. When the monolayer contained only straight-chain molecules (1-octadecanol), the reactive uptake coefficient decreased by a factor of 42 due to the presence of the monolayer. However, when the monolayer contained 0.20 mole fraction of a branched surfactant (phytanic acid) the reactive uptake coefficient only decreased by a factor of 2. Hence, a small amount of branched surfactant drastically changes the overall resistance to reactive uptake. Also, our results show that the overall resistance to reactive uptake of 2-component monolayers can be predicted reasonably accurately by a model that assumes the resistances to mass transfer can be combined in parallel.

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“…Thus, the Eu(EDTA) does not distort the duration of the phase change. Reports by Moore et al 20 and Barnes et al 21 illustrate that at low concentrations (<5%), mixed monolayers show dramatic changes in resistivity21 with no observable changes in the -A isotherm.20 On the basis of the results of Costin and Barnes5 with respect to impurity effects, we would expect the Eu(EDTA) to lengthen the duration of the phase change if it were acting as a soluble impurity. Thus, we believe that the Eu(EDTA) is acting like a low concentration surfactant and not affecting the monolayer's behavior during phase change.…”

Section: Resultsmentioning

confidence: 96%

Evaporation kinetics of ventilated waterdrops coated with octadecanol monolayers

Seaver¹,

Peele²,

Manuccia³

et al. 1992

J. Phys. Chem.

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We have used remote thermometry and video microscopy to monitor simultaneously the temperature and size of evaporating waterdrops coated with monolayers of 1-octadecanol (stearyl alcohol). The experiments are conducted by acoustically levitating individual, 1-3-mm-diameter waterdrops in a 1.5 m/s nitrogen flow conditioned at 0, 35, and 64% relative humidity. We observe a continuous increase in monolayer resistivity as evaporation compresses the monolayer. The change in monolayer resistivity is independent of relative humidity. However, the rate of the resistivity increase is inversely proportional to the relative humidity. Remote drop temperature measurements show that the drop remains in thermal steady state with its surroundings during the monolayer phase change. We show that the additive Eu(EDTA), necessary for remote thermometry, accelerates the onset of the monolayer phase transition and reduces the final resistivity of the monolayer without effecting the monolayer during the phase change. We also discuss the appropriate use of accommodation coefficients and report them when possible.

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The evaporation resistances of octadecanol-cholesterol mixed monolayers

Cited by 14 publications

References 16 publications

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces

Reactive Uptake of N₂O₅on Aqueous H₂SO₄Solutions Coated with 1-Component and 2-Component Monolayers

Evaporation kinetics of ventilated waterdrops coated with octadecanol monolayers

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The evaporation resistances of octadecanol-cholesterol mixed monolayers

Cited by 14 publications

References 16 publications

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces

Surfactant Charge Modulates Structure and Stability of Lipase-Embedded Monolayers at Marine-Relevant Aerosol Surfaces

Reactive Uptake of N2O5on Aqueous H2SO4Solutions Coated with 1-Component and 2-Component Monolayers

Evaporation kinetics of ventilated waterdrops coated with octadecanol monolayers

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Reactive Uptake of N₂O₅on Aqueous H₂SO₄Solutions Coated with 1-Component and 2-Component Monolayers