Article

Mixing of perfluorinated carboxylic acids with dipalmitoylphosphatidylcholine.

Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus #124 IREH, Iowa City 52242-5000 USA.
Biochimica et Biophysica Acta (Impact Factor: 4.66). 09/2004; 1664(2):141-9. DOI: 10.1016/j.bbamem.2004.05.002
Source: PubMed

ABSTRACT Perfluorinated acids are emerging as an important class of persistent environmental pollutant, thus raising human health concerns. To understand the behavior of these compounds in biological systems, the mixing behavior of two perfluorinated acids, perfluorododecanoic and perfluorotetradecanoic acid, with dipalmitoylphosphatidylcholine (DPPC) was studied in monolayers at the air-water interface and in fully hydrated DPPC bilayers. The mixing behavior of both acids was indicative of an attractive interaction and partial miscibility with DPPC at the air-water interface. In the bilayer studies, the fluorinated acids cause peak broadening and elimination of the pretransition of DPPC. The onset temperature of the main phase transition remains constant in the presence of the fluorinated acids suggesting immiscibilities in the gel phase. Below X(DPPC) = 0.97 significant peak broadening of the main phase transition can be observed. These results suggest strong interaction between the respective acid and DPPC, and that both acids are able to partition into the lipid bilayer. However, their mixing behavior is far from ideal, thus suggesting the presence of domains or lipid aggregates with high acid concentrations which may (adversely) impact the function of biological mono- and bilayers.

0 Followers
 · 
69 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In 1861 Thomas Graham gave birth to a new field of science, today known as colloid science. Nowadays, the notion "colloid" is often used referring to systems consisting of two immiscible phases, one of which is finely dispersed into the other. Research on colloids deals mostly with sols (solids dispersed in a liquid), emulsions (liquids dispersed in liquid), and foams (gas dispersed in a liquid). Because the dispersed particles are small, there is a lot of interface per unit mass. Not surprisingly, therefore, the properties of the interface have often a decisive effect on the behaviour of colloids. Water-air interfaces have a special relevance in this field: many water-insoluble molecules can be spread on water and, given the right spreading conditions and enough available surface area, their spreading proceeds until a monolayer (a one-molecule thick layer) eventually remains. Several 2D phases have been identified for such monolayers, like "gas", "liquid expanded", "liquid condensed", and "solid". The central question of this review is whether these 2D phases can also exist as colloidal systems, and what stabilizes the dispersed state in such systems. We shall present several systems capable of yielding 2D phase separation, from those based on either natural or fluorinated amphiphiles, to polymer-based ones. We shall seek for analogies in 3D and we shall try to clarify if the lines between these 2D objects play a similar role as the interfaces between 3D colloidal systems. In particular, we shall consider the special role of molecules that tend to accumulate at the phase boundaries, that is, at the contact lines, which will therefore be denoted "line-actants" (molecules that adsorb at a 1D interface, separating two 2D colloidal entities), by analogy to the term "surfactant" (which indicates a molecule that adsorbs at a 2D interface separating two 3D colloidal entities).
    Chemical Society Reviews 12/2012; 42(5). DOI:10.1039/c2cs35269a · 30.43 Impact Factor
  • Source
    Environmental Science & Technology 11/2012; 46(22). DOI:10.1021/es304430r · 5.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Monolayer surfactant films comprised of a mixture of phospholipids and perfluorinated (or partially fluorinated) surfactants are of potential utility for applications in pulmonary lung surfactant-based therapies. As a simple, minimal model of such a lung surfactant system, binary mixed monolayer films comprised of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and perfluorooctadecanoic acid (C18F) prepared on a simplified lung fluid mimic subphase (pH 7.4, 150 mM NaCl) have been characterized in terms of mixing thermodynamics and compressibility (measured through π-A compression isotherms), film morphology (via atomic force, fluorescence and Brewster angle microscopy), as well as spreading rate and hysteresis response to repeated expansion-contraction cycles for a variety of compositions of mixed films. Under all mixing conditions, films and their components were found to be completely immiscible and phase-separated, though there were significant changes in the aforementioned film properties as a function of composition. Of particular note was the existence of a maximum in the extent of immiscibility (characterized by ∆G_ex^π values) and enhanced surfactant recovery during hysteresis experiments at ΧC18F > 0.30. The latter was attributed to the relatively rapid re-spreading rate of the perfluorinated amphiphile in comparison with DPPC alone at the air-water interface, which enhances the performance of this mixture as a potential pulmonary lung surfactant. Further, monolayer film structure could be tracked dynamically as a function of compression at the air-water interface via Brewster angle microscopy, with the C18F component being preferentially squeezed out of the film with compression, but returning rapidly upon re-expansion. In general, addition of C18F to DPPC monolayers resulted in improvements to mechanical, structural and re-spreading properties of the film, indicating the potential value of these compounds as additives to pulmonary lung surfactant formulations.
    Langmuir 10/2012; 28(43). DOI:10.1021/la3026655 · 4.38 Impact Factor

Full-text (2 Sources)

Download
52 Downloads
Available from
May 21, 2014