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Issue 41, 2015
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Lung surfactants and different contributions to thin film stability

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Abstract

The surfactant lining the walls of the alveoli in the lungs increases pulmonary compliance and prevents collapse of the lung at the end of expiration. In premature born infants, surfactant deficiency causes problems, and lung surfactant replacements are instilled to facilitate breathing. These pulmonary surfactants, which form complex structured fluid–fluid interfaces, need to spread with great efficiency and once in the alveolus they have to form a thin stable film. In the present work, we investigate the mechanisms affecting the stability of surfactant-laden thin films during spreading, using drainage flows from a hemispherical dome. Three commercial lung surfactant replacements Survanta, Curosurf and Infasurf, along with the phospholipid dipalmitoylphosphatidylcholine (DPPC), are used. The surface of the dome can be covered with human alveolar epithelial cells and experiments are conducted at the physiological temperature. Drainage is slowed down due to the presence of all the different lung surfactant replacements and therefore the thin films show enhanced stability. However, a scaling analysis combined with visualization experiments demonstrates that different mechanisms are involved. For Curosurf and Infasurf, Marangoni stresses are essential to impart stability and interfacial shear rheology does not play a role, in agreement with what is observed for simple surfactants. Survanta, which was historically the first natural surfactant used, is rheologically active. For DPPC the dilatational properties play a role. Understanding these different modes of stabilization for natural surfactants can benefit the design of effective synthetic surfactant replacements for treating infant and adult respiratory disorders.

Graphical abstract: Lung surfactants and different contributions to thin film stability

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Publication details

The article was received on 29 Jun 2015, accepted on 13 Aug 2015 and first published on 13 Aug 2015


Article type: Paper
DOI: 10.1039/C5SM01603G
Citation: Soft Matter, 2015,11, 8048-8057
  • Open access: Creative Commons BY-NC license
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    Lung surfactants and different contributions to thin film stability

    E. Hermans, M. Saad Bhamla, P. Kao, G. G. Fuller and J. Vermant, Soft Matter, 2015, 11, 8048
    DOI: 10.1039/C5SM01603G

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