July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Using molecular dynamics simulations to build a nanoscale in silico model of the tear film lipid layer
Author Affiliations & Notes
  • Riku Paananen
    University of Helsinki, Helsinki, Finland
    J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
  • Lukasz Cwiklik
    J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
  • Footnotes
    Commercial Relationships   Riku Paananen, None; Lukasz Cwiklik, None
  • Footnotes
    Support  Czech Granting Agency 17-06792S, NF Neuron, The Finnish Eye Foundation, Evald and Hilda Nissi Foundation, Orion Research Foundation
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 4178. doi:
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    • Get Citation

      Riku Paananen, Lukasz Cwiklik; Using molecular dynamics simulations to build a nanoscale in silico model of the tear film lipid layer. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4178.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Tear film lipid layer (TFLL) covers the aqueous tear film, stabilizing it and preventing excess evaporation of water from the ocular surface. Several models of TFLL organization have been proposed during recent years, but no clear link has been established between the organization and function of TFLL. To tackle this problem, the purpose of this study was to build an in silico molecular dynamics simulation model of the TFLL, which encompasses the current knowledge of TFLL composition and organization. Specifically, to include wax esters (WEs) and cholesteryl esters (CEs) as the main nonpolar lipids and (O-acyl)-ω-hydroxy fatty acids (OAHFAs) as the main polar lipids, as well as include enough detail in order to capture the crystalline ordering of these lipids.

Methods : All-atom molecular dynamics simulation model was developed for WEs, CEs, and OAHFAs. The simulation model was validated by comparing simulated properties with experimentally determined densities and melting points, as well as Langmuir monolayer experiments. Mixed films of WEs, CEs and OAHFAs were simulated on an aqueous subphase. Simulations were performed for laterally relaxed and compressed films with varying lipid compositions.

Results : Good agreement with experimental results was obtained for each simulated lipid class individually. Simulations of mixed systems showed that OAHFAs improved the spreading of nonpolar WEs and CEs as disordered films. Lateral compression of mixed films resulted in development of crystalline order in the studied systems. Qualitative agreement was observed between the simulated TFLL model and experiments.

Conclusions : The developed in silico model shows high potential in providing molecular level insight into the structure of the TFLL, especially since in encompasses the major lipids components of the TFLL and the results can be readily compared with experimental results from Langmuir monolayer experiments.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

 

Figure 1. Representative lipids from each lipid class included in the molecular dynamics simulation model.

Figure 1. Representative lipids from each lipid class included in the molecular dynamics simulation model.

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