Fluidization of a dipalmitoyl phosphatidylcholine monolayer by fluorocarbon gases. Potential use in lung surfactant therapy
Gerber Frédéric 1, Krafft Marie Pierre 2*, Vandamme F. Thierry 3, Goldmann Michel 4 and Fontaine Philippe 5
1 Institut Charles sadron (CNRS)
2 Institut Charles Sadron (CNRS)
3 Laboratoire de Chimie Bioorganique
4 Institut des Nanosciences de Paris
5 Synchrotron SOLEIL
* To whom correspondence should be addressed. E-mail: krafft{at}ics.u-strasbg.fr.
Submitted on November 1, 2005
Revised on November 28, 2005
Accepted on 10 January 2006
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Abstract |
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Fluorocarbon gases (gFCs) were found to inhibit the liquid-expanded (LE) / liquid-condensed (LC) phase transition of dipalmitoylphosphatidylcholine (DPPC) Langmuir monolayers. The formation of domains of a LC phase, which typically occurs in the LE / LC coexistence region upon compression of DPPC, is prevented when the atmosphere above the DPPC monolayer is saturated with a gFC. When contacted with gFC, the DPPC monolayer remains in the LE phase for surface pressures lower than 38 mN m-1, as assessed by compression isotherms and fluorescence microscopy (FM). Moreover, gFCs can induce the dissolution of pre-existing LC phase domains and facilitate the re-spreading of the DPPC molecules on the water surface, as shown by FM and grazing incidence X-ray diffraction. gFCs have thus a highly effective fluidizing effect on the DPPC monolayer. This gFC-induced fluidizing effect was compared with the fluidizing effect brought about by a mixture of unsaturated lipids and proteins, namely the two commercially available lung surfactant substitutes, Curosurf® and Survanta®, which are derived from porcine and bovine lung extracts, respectively. The candidate FCs were chosen among those already investigated for biomedical applications, and in particular for intravascular oxygen transport, i.e. perfluorooctyl bromide, perfluorooctylethane, bis(perfluorobutyl)ethene, perfluorodecalin and perfluorooctane. The fluidizing effect is most effective with the linear FCs. This study suggests that FCs, whose biocompatibility is well documented, may be useful in lung surfactant substitute compositions.
Key Words:
DPPC monolayer, Fluorescence microscopy, Fluorocarbon, Grazing incidence X-ray diffraction, Lung surfactant, Perfluorooctyl bromide
