Langmuir films and mechanical properties of polyethyleneglycol fatty acid esters at the air-water interface

Ortiz-Collazos, Stephanie; Gonçalves, Yan M H; Horta, Bruno A. C.; Picciani, Paulo H. S.; Louro, Sônia R.W.; Oliveira, Osvaldo N.; Pimentel, André Silva

doi:10.1016/j.colsurfa.2016.03.032

Cited by 17 publications

(10 citation statements)

References 51 publications

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“…Introducing the virial equation, Equation (2), in the former equations, then Equation (10) is obtained for the excess free energy, G E , which can be calculated from the values of the virial coefficients according to Equations (11)- (13). This treatment is rarely seen in bibliography, and offers an alternative way to calculate excess free energy values.…”

Section: Methodsmentioning

confidence: 99%

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Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Torrent‐Burgués

2018

Colloids and Interfaces

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Mixed fatty acids or mixed phospholipids systems with saturated-unsaturated hydrocarbon chains are of biological interest. In this work, the monolayers of oleic acid-stearic acid (OA-SA) and palmitoyloleoylphosphatidylcholine-dipalmitoylphosphatidylcholine (POPC-DPPC) have been studied. From the surface pressure-area isotherms, elastic modulus values and virial equation coefficients can be obtained. Thermodynamic treatment also yields excess (G E ) and mixing (∆G mix ) free energies. Results indicate positive G E values, that is, molecular interactions in the mixed films are less favourable, due to the presence of unsaturation; however, the mixture is slightly favourable due to the entropic factor that affords positive ∆G mix values. For the OA-SA system, a high SA content and surface pressure facilitate the phase separation, even though a certain miscibility between both components still remains. For the POPC-DPPC system, the most favourable mixing conditions occur for X POPC ≈ 0.4. For these mixed systems, the values of the elastic modulus are more similar to those of more fluid components (OA or POPC); analysis of the virial coefficients shows that the b 1 virial coefficient values lie between those of the individual components and are higher than values suitable for an ideal mixing.

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Section: Methodsmentioning

confidence: 99%

“…Bibliographic references to previous studies can be found in [1][2][3]. Articles on single component fatty acids or related amphiphiles published in the last years are those of [4][5][6][7][8][9][10][11][12][13][14][15][16], and articles on single component phospholipids are those of [17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Torrent‐Burgués

2018

Colloids and Interfaces

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“…Unfortunately, a pure sample of the complex of pgdpt , [Fe II ( pgdpt ) 2 (NCBH 3 ) 2 ], proved elusive because instead it formed mixtures of the desired complex and starting material [Fe(pyridine) 4 (NCBH 3 ) 2 ]. Hence, although we have previously shown that Rdpt ‐type ligands suitably functionalised with long‐alkyl chain tails are capable of forming stable Langmuir films, and it is known from other studies that PEG tails can also confer film‐forming properties, such studies have not been performed on the pgdpt system.…”

Section: Resultsmentioning

confidence: 99%

Towards Dual‐Functionality Spin‐Crossover Complexes

et al. 2018

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The multistep synthesis of a versatile new 4‐substituted 3,5‐bis(2‐pyridyl)‐1,2,4‐triazole (Rdpt) ligand, 4‐[4‐(2‐aminomethyl)phenyl]‐3,5‐bis(2‐pyridyl)‐4 H‐1,2,4‐triazole (apdpt), is reported, which features a reactive aminomethyl para‐substituent on the phenyl group that points “out of the back” of the triazole. This enables further functionalisation under mild conditions by using a range of esters to form an amide link. Specifically, this proof of principle study demonstrates the synthesis of apdpt successfully appended with gold‐binding thioctic acid (tpdpt), graphene‐binding/emissive pyrene/propylpyrene (prdpt/pbdpt), and a Langmuir–Blodgett film‐forming polyethylene glycol (PEG) tail (pgdpt). These ligands are subsequently reacted with [Fe(pyridine)4(NCBH3)2] to give the mononuclear iron(II) complexes [Fe(Rdpt)2(NCBH3)2]⋅solvent, in which Rdpt/solvent is tpdpt/2.5 H2O (1), prdpt/0.5 CHCl3⋅H2O (2), and pbdpt/0.5 CHCl3⋅2 H2O (3), as red powders. Magnetic studies on these powders indicate that the complexes undergo only very gradual and incomplete spin crossover, from completely or mostly high spin at 300 K, to half or three‐quarters high spin at 50 K. Gold nanoparticles are successfully functionalised with the thioctic acid tpdpt ligand to give tpdpt@Au with an average diameter (as determined by TEM) of (3.1±0.7) nm. Preliminary studies on the two pyrene systems in dimethylformamide show that upon excitation at λ=345 nm the blue fluorescence observed for the free ligands is retained, essentially unaffected, in the respective complexes.

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“…For example, Chimote and Banerjee(CHIMOTE; BANERJEE, 2005b) observed that rifampicin, isoniazide, and ethambutol interact with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers, even increasing the monolayer surface activity in some cases, which may imply that these antibiotics could be administered mixed in the pulmonary surfactant. Levofloxacin was observed to expand the lung surfactant film, stabilizing it without changing its elasticity (ORTIZ-COLLAZOS et al, 2017a). In contrast, BANERJEE, 2005c) reported that the mycobacterial lipids (mycolic acid and cord factor) affect…”

Section: Clarithromycin Does Not Affect the Stability Of A Lung Surfamentioning

confidence: 98%

“…This study was financed in part by the The Langmuir technique allows the formation of phospholipid monolayers at the air-water interface which may be used as the simplest model of a biological membrane to investigate the interactions with species such as drugs, toxins or pollutants MÖHWALD, 2003;DELEU;PAQUOT;NYLANDER, 2005;GRIFFITH et al, 2013;ORTIZ-COLLAZOS et al, 2017b). This approach is especially convenient since the monolayer stability may be investigated (GRIFFITH et al, 2013;ORTIZ-COLLAZOS et al, 2016, 2017bPANTOJA-ROMERO et al, 2016) and the compounds can be purposefully added to the subphase at a controlled concentration (GRIFFITH et al, 2013;HAC-WYDRO;DYNAROWICZ-ŁATKA, 2006;JABŁONOWSKA;BILEWICZ, 2007) or mixed with the lipid monolayer (ORTIZ-COLLAZOS et al, 2017b). 1,2-dipalmitoyl-sn-glycero-3phosphocholine (DPPC) is the most important and abundant phospholipid occurring in natural membranes.…”

Section: 4mentioning

confidence: 99%

Physical-Chemical Studies of the Effect of Antibiotic Incorporation in the Structure and Molecular Organization of Clinical-Grade Lung Surfactant Monolayers and Membrane Models at the Air-Water Interface

COLLAZOS¹

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Langmuir films and mechanical properties of polyethyleneglycol fatty acid esters at the air-water interface

Cited by 17 publications

References 51 publications

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Thermodynamic Behaviour of Mixed Films of an Unsaturated and a Saturated Polar Lipid. (Oleic Acid-Stearic Acid and POPC-DPPC)

Towards Dual‐Functionality Spin‐Crossover Complexes

Physical-Chemical Studies of the Effect of Antibiotic Incorporation in the Structure and Molecular Organization of Clinical-Grade Lung Surfactant Monolayers and Membrane Models at the Air-Water Interface

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