Back to Search
Start Over
Evaporation retardation by model tear-lipid films: The roles of film aging, compositions and interfacial rheological properties.
- Source :
-
Colloids & Surfaces B: Biointerfaces . Jan2021, Vol. 197, pN.PAG-N.PAG. 1p. - Publication Year :
- 2021
-
Abstract
- • A new methodology for long-term evaporation evaluation is developed. • A slow water-evaporation through human and model lipid films in vitro is verified. • Evaporation in vitro reduces as lipid nanofilms mature to form specific structures. • Saturated phospholipids enhance evaporation reductions by mixed lipid films. • The similarity between model lipids and human tear-lipids interfacial rheology is achieved. A novel methodology for assessing evaporation (up to 48 h) through lipid-nanofilms in vitro was developed. The influence of lipid-mixture compositions on evaporation rates was studied. The evaporative fluxes and rheology of lipid-nanofilms were compared with those of human tear-lipid nanofilms in vitro.A sessile-drop technique with precise drop-volume control was adapted to measure evaporation rates at constant temperature of 36 °C and humidity of 75 %. Model lipid solutions were deposited on the surface of aqueous drops to create nanofilms of 10–100 nm. The measurements of dynamic surface pressure vs. nanofilm-thickness were performed under the same conditions. The lipid-mixtures compositions were chosen to mimic that of human tear lipids. Evaporation through lipid nanofilms decreased with film thickness and aging. Evaporation through 70-nm films was 2.5–3 time slower than through 10-nm-thick films. Nonpolar-lipid mixtures reduced evaporation by approximately 35 %. The optimized model-lipid mixtures containing polar phospholipids reduced evaporation by 70–75 %, matching the evaporation-reduction by human-lipid nanofilms in vitro. These model mixtures exhibited interfacial rheology similar to human tear lipids in vitro.This methodology substantiated that aged lipid-nanofilms significantly reduced evaporation in vitro. These findings contradict to the previous reports suggesting that model lipid and meibum films do not retard evaporation in vitro. Polar phospholipids enhance evaporative resistance close to the level observed for human tear-lipid films in vivo. We hypothesize that unique rheological properties of tear-lipid nanofilms are germane to the specific mono- and bi-layered structures formed by phospholipids at the lipid-air and lipid-aqueous interfaces. [ABSTRACT FROM AUTHOR]
- Subjects :
- *SURFACE pressure
*DYNAMIC pressure
*NANOFILMS
*LIPIDS
*GALACTOSE
*PHOSPHOLIPIDS
Subjects
Details
- Language :
- English
- ISSN :
- 09277765
- Volume :
- 197
- Database :
- Academic Search Index
- Journal :
- Colloids & Surfaces B: Biointerfaces
- Publication Type :
- Academic Journal
- Accession number :
- 147550373
- Full Text :
- https://doi.org/10.1016/j.colsurfb.2020.111392