The tear film at the ocular surface is covered by a thin layer of lipids. This oily phase stabilizes the film by decreasing its surface tension and improving its viscoelastic properties. Clinically, destabilization and rupture of the tear film are related to dry eye disease and are accompanied by changes in the quality and quantity of tear film lipids. In dry eye, eye drops containing oil-in-water emulsions are used for the supplementation of lipids and surface-active components to the tear film. We explore in detail the biophysical aspects of interactions of specific surface-active compounds, cetalkonium chloride and poloxamer 188, which are present in oil-in-water emulsions, with tear lipids. The aim is to better understand the macroscopically observed eye drops-tear film interactions by rationalizing them at the molecular level. To this end, we employ a multi-scale approach combining experiments on human meibomian lipid extracts, measurements using synthetic lipid films, and in silico molecular dynamics simulations. By combining these methods, we demonstrate that the studied compounds specifically interact with the tear lipid film enhancing its structure, surfactant properties, and elasticity. The observed effects are cooperative and can be further modulated by material packing at the tear-air interface.

• Klíčová slova
• Langmuir trough, dilatation rheology, fluorescence microscopy, meibum, molecular dynamics, tear film, tear film lipid layer,
• MeSH
• fluorescenční mikroskopie * metody   MeSH
• kvartérní amoniové sloučeniny chemie   MeSH
• lidé MeSH
• lipidy * chemie   MeSH
• mastné alkoholy chemie   MeSH
• meibomské žlázky metabolismus   MeSH
• poloxamer chemie   MeSH
• simulace molekulární dynamiky * MeSH
• slzy * chemie   MeSH
• teoretické modely MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cetalkonium chloride MeSH Prohlížeč
• kvartérní amoniové sloučeniny MeSH
• lipidy * MeSH
• mastné alkoholy MeSH
• poloxamer MeSH

Tear film lipid layer is a complex lipid mixture forming the outermost interface between eye and environment. Its key characteristics, such as surface tension and structural stability, are governed by the presence of polar lipids. The origin of these lipids and exact composition of the mixture are still elusive. We focus on two minor polar lipid components of the tear film lipid later: sphingomyelin and ceramide. By employing coarse grain molecular dynamics in silico simulations accompanied by Langmuir balance experiments we provide molecular-level insight into behavior of these two lipids in a tear film lipid layer model. Sphingomyelin headgroups are significantly exposed at the water-lipids boundary while ceramide molecules are incorporated between other lipids frequently interacting with nonpolar lipids. Even though these two lipids increase surface tension of the film, their molecular-level behavior suggests that they have a stabilizing effect on the tear film lipid layer.

• Klíčová slova
• Ceramide, Langmuir balance, Molecular dynamics simulations, Sphingomyelin, Tear film lipid layer,
• MeSH
• ceramidy chemie   MeSH
• estery cholesterolu chemie   MeSH
• lidé MeSH
• lipidy chemie   MeSH
• meibomské žlázky chemie   metabolismus   MeSH
• povrchové napětí MeSH
• sfingomyeliny chemie   MeSH
• simulace molekulární dynamiky MeSH
• slzy chemie   MeSH
• termodynamika MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ceramidy MeSH
• estery cholesterolu MeSH
• lipidy MeSH
• sfingomyeliny MeSH