Structural-Dilatational Characteristics Relationships of Monoglyceride Monolayers at the Air−Water Interface

Patino, Juan M. Rodrı́guez; Sánchez, Cecilio Carrera; Niño, and Ma. Rosario Rodríguez; Fernández, Marta Cejudo

doi:10.1021/la0017375

Cited by 78 publications

(41 citation statements)

References 46 publications

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“…Structural and Topographical Characteristics. Results derived from π− A isotherms (Figure A) in the modified Wilhelmy type trough are in good agreement with those obtained in the same unmodified trough with pure β-casein and monopalmitin monolayers and in the Langmuir type trough with the same β-casein, monopalmitin, and β-casein−monopalmitin mixed films. , Briefly, the results of π− A isotherms confirm that β-casein monolayers at the air−water interface adopt two different structures and the collapse phase. At low surface pressures, β-casein molecules may exist as trains with all amino acid segments located at the interface .…”

Section: Resultssupporting

confidence: 82%

“…Surface Film Balance. Measurements of the surface pressure (π) versus average area per molecule ( A ) were performed on the same modified Wilhelmy type film balance, as described elsewhere. , The measurement of the π− A isotherm was performed before the experiments of surface shear rheology. This isotherm was recorded with the maximum width of the canal at which the surface pressure at both sides of the canal was the same (i.e., Δπ was zero during the monolayer compression).…”

Section: Methodsmentioning

confidence: 99%

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Flow-Induced Molecular Segregation in β-Casein−Monoglyceride Mixed Films Spread at the Air−Water Interface

Sánchez

Patino

2004

Langmuir

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In this work, we have used different and complementary interfacial techniques (surface film balance, Brewster angle microscopy, and interfacial shear rheology) to analyze the static (structure, topography, reflectivity, miscibility, and interactions) and flow characteristics (surface shear characteristics) of beta-casein and monoglyceride (monopalmitin and monoolein) mixed films spread on the air-water interface. The structural, topographical, and shear characteristics of the mixed films depend on the surface pressure and on the composition of the mixed film. The surface shear viscosity (etas) varies greatly with the surface pressure. In general, the greater the surface pressure, the greater the values of etas. At higher surface pressures, collapsed beta-casein residues may be displaced from the interface by monoglyceride molecules with important repercussions on the shear characteristics of the mixed films. A shear-induced change in the topography of monoglyceride and beta-casein domains, on one hand, and a segregation between domains of the film-forming components, on the other hand, were also observed. The displacement of the beta-casein by the monoglycerides is facilitated under shear conditions, especially for beta-casein-monoolein mixed films.

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Section: Resultssupporting

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Flow-Induced Molecular Segregation in β-Casein−Monoglyceride Mixed Films Spread at the Air−Water Interface

Sánchez

Patino

2004

Langmuir

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“…Besides fatty acids, the monoalkanoylglycerolesters are the most studied amphiphiles in the bulk and at the air–water interface. Palmitoyl- and stearoyl-glycerol, as the most used homologues of saturated monoalkanoylglycerols for practical applications, have been intensively studied. − Systematic studies of the influence of the chemical structure as well as chirality effects on structural properties provide general information on the two-dimensional characteristics. − In previous papers, racemic 1-monopalmitoyl- rac -glycerol and 1-monostearoyl- rac -glycerol monolayers have been used allowing conclusions on other homologues 1-monoalkanoyl- rac -glycerol monolayers. The studies of the two-dimensional lattice structures in the accessible temperature and pressure regions resulted in the construction of the generic π– T phase diagram of monoalkanoylglycerolester monolayers.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Alkanoyl Group Position at the Glycerol Backbone on the Monolayer Characteristics Demonstrated by 2-Monopalmitoyl-rac-glycerol

et al. 2017

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The influence of the position of the aliphatic chain at the glycerol backbone has been basically unknown. Solely the results of 2-monopalmitoyl-rac-glycerol obtained at ≥13 °C indicated an essential influence of the position of the palmitoyl group at the glycerol backbone, substantiated by a disordered packing of the alkyl chains. Therefore, the present study extends the comprehensive characterization of 2-monopalmitoyl-rac-glycerol monolayers to the low-temperature range for highlighting the effect of the position of the aliphatic chain at the glycerol backbone of monoalkanoylglycerolester monolayers. Systematic studies of the thermodynamic behavior, the morphological features, and the 2D lattice structures of 2-monopalmitoyl-rac-glycerol monolayers at ≤10 °C allow useful conclusions. Large differences between the π-A isotherms of 1- and 2-monopalmitoyl-rac-glycerol monolayers and their thermodynamic analysis indicate that the change of the substitution from position 1 to position 2 of glycerol backbone is consistent with a shortening of the alkyl chain by roughly two CH groups. Quantum chemical calculations of the molecular structure and packing calculations are in reasonable agreement with the thermodynamic results. Considerable diversity in the mesoscopic domain topography exists between the monoalkanoylglycerol esters with the aliphatic chain positioned at the end of the glycerol backbone (1-position) and those with the aliphatic chain in the middle of the glycerol backbone (2-position). The new faceted shape of the 2-monopalmitoyl-rac-glycerol domains, before they develop branched fractal-like structures at the edges, is the essential difference to the round or cardioid-like 1-monoalkanoylglycerol domains. In the low-temperature range, well-defined orthorhombic lattice structures exist at all surface pressures. Comparing all GIXD data from the three racemic compounds (1-monostearoyl-rac-glycerol, 1-monopalmitoyl-rac-glycerol, and 2-monopalmitoyl-rac-glycerol) shows that 2-monopalmitoyl-rac-glycerol behaves as 1-monomyristoyl-rac-glycerol, i.e., the shift from position 1 to position 2 of the glycerol backbone is equivalent to a shortening of the alkyl chain.

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“…The mimetic monolayers have the advantage of being well defined and of providing a large variability in density. Palmitoyl and stearoylglycerol have been the most examined monolayers of the saturated monoacylglycerols because of their omnipresence in biological and applied systems. − …”

Section: Introductionmentioning

confidence: 99%

Phase Characteristics of 1-Monopalmitoyl-rac-glycerol Monolayers at the Air/Water Interface

Vollhardt

Brezesinski

2016

Langmuir

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1-Monopalmitoyl-rac-glycerol is omnipresent in numerous biological and applied systems. Systematic GIXD measurements of 1-monopalmitoyl-rac-glycerol monolayers are carried out over a large pressure interval at 5, 10, and 15 °C to construct the phase diagram on the basis of reliable 2D lattice structures. These studies are complemented by other monolayer characteristics, such as π-A isotherms and mesoscopic domain topographies. A phase transition is found between the two orthorhombic structures with NN and NNN tilted alkyl chains at low temperatures (5 and 10 °C). It increases linearly with increasing temperature. With a further increase in temperature to 15 °C, only NN-tilted orthorhombic lattices are observed in the whole pressure region. The cross-sectional area, A0, is less affected by surface pressure and temperature and amounts to values of between 19.7 and 19.8 Å(2), as expected for a rotator phase at the lower limit. The tilt angle t with respect to the surface normal decreases with increasing pressure and is only slightly influenced by the temperature. The transition pressure to untilted alkyl chains, as determined by the extrapolation of 1/cos(t) to zero tilt angle, is >50 mN/m for all temperatures. The results of lattice distortion d versus sin 2(t) suggest for 10 and 15 °C the tilt of the aliphatic chains as the reason for the monolayer lattice distortion whereas at 5 °C the nonzero-tilt-angle intercept d0 could be an indication of the prevention of hexagonal packing. The generic π-T phase diagram of racemic monoacylglycerol monolayers is constructed on the basis of the phase diagrams of 1-monopalmitoyl-rac-glycerol and 1-monostearoyl-rac-glycerol, which shows that for 1-monopalmitoyl-rac-glycerol monolayers the oblique phase can occur only close to and below 0 °C. The possible phase behavior of other racemic monoacylglycerol monolayers with alkyl chain lengths of C14 and C20 is discussed on the basis of the generic phase diagram.

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Structural-Dilatational Characteristics Relationships of Monoglyceride Monolayers at the Air−Water Interface

Cited by 78 publications

References 46 publications

Flow-Induced Molecular Segregation in β-Casein−Monoglyceride Mixed Films Spread at the Air−Water Interface

Flow-Induced Molecular Segregation in β-Casein−Monoglyceride Mixed Films Spread at the Air−Water Interface

Effect of the Alkanoyl Group Position at the Glycerol Backbone on the Monolayer Characteristics Demonstrated by 2-Monopalmitoyl-rac-glycerol

Phase Characteristics of 1-Monopalmitoyl-rac-glycerol Monolayers at the Air/Water Interface

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