Purchase this article with an account.
T. J. Millar, S. R. Raju, H. A. Ketelson; The Effect of a Di-Block Copolymer, Poly(oxyethylene)-Poly(oxybutylene), on the Viscoelastic Properties of Human Meibomian Lipid Films. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4152.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Amphiphilic block copolymers have unique interfacial properties and can offer potential uses for eye care applications such as contact lenses and dry eye. Well defined di-block copolymers, poly(oxyethylene)-poly(oxybutylene) (EOBO), were synthesized and the purpose of this study was to evaluate their interfacial properties in the presence of lipids and proteins. We have investigated its effects on the viscoelastic properties and interfacial tension of Meibomian lipid films.
Human Meibomian lipids were dissolved at a known concentration in hexane and then spread onto the surface of a pendant drop of artificial tear buffer (ATB) hanging from a stainless steel needle. Either EOBO alone, or an EOBO-lysozyme mixture, dissolved in ATB, was injected into the lipid coated drop. Interfacial tension was calculated by drop shape analysis. Viscoelasticity was calculated by oscillating the drop (via sine wave function) at a range of frequencies covering three orders of magnitude. Experiments were conducted at 20°C and 37°C.
As oscillation frequency increased, the complex dilatational modulus of Meibomian lipids increased from 55-100mN/m at 20°C and 35-55mN/m at 37°C. In the presence of EOBO, the modulus was lower and increased from 35-65mN/m at 20°C and 20-45mN/m at 37°C. In the presence of lysozyme, the viscoelasticity of Meibomian lipid films increased, but this was reduced by the addition of EOBO. Viscoelasticity decreased from 70-120mN/m to 60-62mN/m at 20°C and from 50-70mN/m to 37-55mN/m at 37°C. The interfacial tension of an EOBO film was minimally affected by the presence of Meibomian lipids, lysozyme or a combination of both.
The decrease in viscoelasticity of the Meibomian lipid film in the presence of EOBO could be because the lipid film is weakened and destabilized by this polymer. However, due to the lack of change in interfacial tension, it is more likely that the EOBO molecules have blocked and displaced the lipid and/or protein molecules off the surface. For a better understanding of how this polymer may behave physiologically, the interaction of EOBO with whole tears needs investigation. These data also indicate that EOBO might be used in future experiments to determine its ability to prevent lipid and protein deposition on contact lenses.
This PDF is available to Subscribers Only