Mixing of Saturated and Unsaturated Phosphatidylcholines and Phosphatidylglycerols in Monolayers at the Air/Water Interface

Koppenol, Sandy; Yu, Hyuk; Zografi, George

doi:10.1006/jcis.1997.4823

Cited by 29 publications

(22 citation statements)

References 28 publications

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“…The presence of Na + as a counter‐ion would appear possibly to make a difference in the ability of water to be removed with decreasing RH. The remarkably identical properties of DPPC and DPPG and of POPC and POPG in the highly hydrated state, despite very different polar group structures and very different behavior at lower relative humidities, confirms the results of monolayer and bilayer studies of these phospholipids,29,44 showing identical values of T m and near ideal mixing of PC and PG with the same acyl chains.…”

Section: Discussionsupporting

confidence: 73%

“…This manner of analyzing the hydration of these phospholipid bilayers is supported by the results with the monounsaturated derivatives, where the presence of the cis double bond at the Δ9 position of the oleoyl chain would be expected, based upon previously reported surface chemical and biophysical studies on phospholipid bilayer and monolayer spreading, packing, and phase behavior at the air–water interface,29,38 to prevent lateral packing in the bilayer as close as that which occurs with the disaturated compounds, presumably allowing more availability of water for the polar region of the bilayer. In Table 4, however, it can be noted that POPC and POPG exhibit a significant increase in first critical RH (from the vapor absorption isotherm) when compared to their corresponding disaturated derivatives, and, thus, more resistance to water uptake.…”

Section: Discussionmentioning

confidence: 55%

“…In view of the very different properties of the PC and PG headgroups, in terms of net charge, molecular size, presence or absence of Na + , and intermolecular hydrogen‐bonding, it is remarkable that these properties would compensate so well to give essentially identical phase behavior at full hydration, and full hydration at the same level of water content. It is intriguing to ask whether or not this bears any relationship to the possible role of these polar groups in certain biological situations, where both are present, such as in the case of pulmonary surfactant where mixtures of DPPC and DPPG form ideally mixed monolayers and bilayers with physiological implications 29–31…”

Section: Discussionmentioning

confidence: 99%

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The relationship between water vapor absorption and desorption by phospholipids and bilayer phase transitions

Mansour

Zografi

2007

Journal of Pharmaceutical Sciences

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 99%

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The relationship between water vapor absorption and desorption by phospholipids and bilayer phase transitions

Mansour

Zografi

2007

Journal of Pharmaceutical Sciences

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“…It was used at a level of 1% in the spread monolayer, a level previously shown not to affect the properties of the monolayer. 36,37 …”

Section: Methodsmentioning

confidence: 98%

Relationships between Equilibrium Spreading Pressure and Phase Equilibria of Phospholipid Bilayers and Monolayers at the Air−Water Interface

2007

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The intricate interplay between the bilayer and monolayer properties of phosphatidylcholine (PC), phosphatidylglycerol (PG), and phosphatidylethanolamine (PE) phospholipids, in relation to their polar headgroup properties, and the effects of chain permutations on those polar headgroup properties have been demonstrated for the first time with a set of time-independent bilayer-monolayer equilibria studies. Bilayer and monolayer phase behavior for PE is quite different than that observed for PC and PG. This difference is attributed to the characteristic biophysical PE polar headgroup property of favorable intermolecular hydrogen-bonding and electrostatic interactions in both the bilayer and monolayer states. This characteristic hydrogen-bonding ability of the PE polar headgroup is reflected in the condensed nature of PE monolayers and a decrease in equilibrium monolayer collapse pressure at temperatures below the monolayer critical temperature, T(c) (whether above or below the monolayer triple point temperature, T(t)). This interesting phenomena is compared to equilibrated PC and PG monolayers which collapse to form bilayers at 45 mN/m at temperatures both above and below monolayer T(c). Additionally, it has been demonstrated by measurements of the equilibrium spreading pressure, pie, that at temperatures above the bilayer main gel-to-liquid-crystalline phase-transition temperature, T(m), all liquid-crystalline phospholipid bilayers spread to form monolayers with pie around 45 mN/m, and spread liquid-expanded equilibrated monolayers collapse at 45 mN/m to form their respective thermodynamically stable liquid-crystalline bilayers. At temperatures below bilayer T(m), PC and PG gel bilayers exhibit a drop in bilayer pi(e) values < or =0.2 mN/m forming gaseous monolayers, whereas the value of pic of spread monolayers remains around 45 mN/m. This suggests that spread equilibrated PC and PG monolayers collapse to a metastable liquid-crystalline bilayer structure at temperatures below bilayer T(m) (where the thermodynamically stable bilayer liquid-crystalline phase does not exist) and with a surface pressure of 45 mN/m, a surface chemical property characteristically observed at temperatures above bilayer T(m) (monolayer T(c)). In contrast, PE gel bilayers, which exist at temperatures below bilayer T(m) but above bilayer T(s) (bilayer crystal-to-gel phase-transition temperature), exhibit gel bilayer spreading to form equilibrated monolayers with intermediate pie values in the range of 30-40 mN/m; however, bilayer pie and monolayer pic values remain equal in value to one another. Contrastingly, at temperatures below bilayer T(s), PE crystalline bilayers exhibit bilayer pie values < or =0.2 mN/m forming equilibrated gaseous monolayers, whereas spread monolayers collapse at a value of pic remaining around 30 mN/m, indicative of metastable gel bilayer formation.

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“…Phase-separated binary phospholipid mixtures have been more commonly examined in-situ by fluorescence microscopy [14][15][16][17][18] and in transferred films by AFM [15,[19][20][21], but it is also possible to observe the segregation by BAM. Phase-separated binary phospholipid mixtures have been more commonly examined in-situ by fluorescence microscopy [14][15][16][17][18] and in transferred films by AFM [15,[19][20][21], but it is also possible to observe the segregation by BAM.…”

Section: Discussionmentioning

confidence: 99%

Calcium Oxalate Monohydrate Precipitation at Phospholipid Monolayer Phase Boundaries

Benitez

Talham

2004

MRS Proc.

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The precipitation of calcium oxalate monohydrate (COM) was observed at biphasic phospholipid Langmuir monolayers with the aid of Brewster angle microscopy. COM appears preferentially at phase boundaries of a monolayer of 1,2-dipalmitoyl-sn-glycero-3phosphocholine (DPPC) in a state of liquid expanded/liquid condensed coexistance. However, when the phase boundary is created by two different phospholipids that are phase segregated, such as DPPC and 1,2-dimiristoyl-sn-glycero-3-phosphocholine (DMPC), crystal formation occurs away from the interface. It is suggested that COM growth at phase boundaries is preferred only when there is molecular exchange between the phases.

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Mixing of Saturated and Unsaturated Phosphatidylcholines and Phosphatidylglycerols in Monolayers at the Air/Water Interface

Cited by 29 publications

References 28 publications

The relationship between water vapor absorption and desorption by phospholipids and bilayer phase transitions

The relationship between water vapor absorption and desorption by phospholipids and bilayer phase transitions

Relationships between Equilibrium Spreading Pressure and Phase Equilibria of Phospholipid Bilayers and Monolayers at the Air−Water Interface

Calcium Oxalate Monohydrate Precipitation at Phospholipid Monolayer Phase Boundaries

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