Molecular organization of the tear fluid lipid layer

Pipsa Kulovesi, Jelena Telenius, Artturi Koivuniemi, Gerald Brezesinski, Antti Rantamäki, Tapani Viitala, Esa Puukilainen, Mikko Ritala, Susanne K. Wiedmer, Ilpo Vattulainen, Juha M. Holopainen

Research output: Contribution to journalArticleScientificpeer-review

65 Citations (Scopus)


The tear fluid protects the corneal epithelium from drying out as well as from invasion by pathogens. It also provides cell nutrients. Similarly to lung surfactant, it is composed of an aqueous phase covered by a lipid layer. Here we describe the molecular organization of the anterior lipid layer of the tear film. Artificial tear fluid lipid layers (ATFLLs) composed of egg yolk phosphatidylcholine (60 mol %), free fatty acids (20 mol %), cholesteryl oleate (10 mol %), and triglycerides (10 mol %) were deposited on the air-water interface and their physico-chemical behavior was compared to egg-yolk phosphatidylcholine monolayers by using Langmuir-film balance techniques, x-ray diffraction, and imaging techniques as well as in silico molecular level simulations. At low surface pressures, ATFLLs were organized at the air-water interface as heterogeneous monomolecular films. Upon compression the ATFLLs collapsed toward the air phase and formed hemispherelike lipid aggregates. This transition was reversible upon relaxation. These results were confirmed by molecular-level simulations of ATFLL, which further provided molecular-scale insight into the molecular distributions inside and dynamics of the tear film. Similar type of behavior is observed in lung surfactant but the folding takes place toward the aqueous phase. The results provide novel information of the function of lipids in the tear fluid.

Original languageEnglish
Pages (from-to)2559-2567
Number of pages9
JournalBiophysical Journal
Issue number8
Publication statusPublished - 20 Oct 2010
Externally publishedYes
MoE publication typeA1 Journal article-refereed


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