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Jan Oscar Pralits, Rodolfo Repetto, Irene Nepita, Mario R Romano, Francesca Ravera, Eva Santini, Libero Liggieri; The effect of albumin on the interfacial tension of silicone oil in vitrectomized eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5006. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The formation and stability of emulsions in vitrectomized eyes is linked to the properties of the silicone oil-aqueous humor interface, in particular the surface tension. In the presence of natural surfactants, such as serum and plasma, the value of the surface tension is likely to change, but little quantitative information is presently available. To this end we perform accurate experiments measuring the interfacial properties of silicone oil (Siluron 1000) with anaqueous solution in the presence of endogenous-like proteins that can act as surfactants.
The interfacial tension (IT) and the interfacial dilational viscoelasticity (the response of interfacial tension to oscillatory perturbations of the interfacial area) have been measured at 35°C for the interface between silicone oil and albumin solutions (7 g/L, 35 g/L, 70 g/L) in a Dulbecco alkaline buffer. This represents an initial model system to investigate the interfacial properties of silicone oil in a vitrectomized eye. Measurements were performed using a Drop Shape Dynamic Tensiometer (PAT1-Sinterface, Berlin).
The presence of albumin affects remarkably the interfacial properties. For the investigated albumin concentrations figure 1 reports the ratio between the equilibrium values of IT in the presence of albumin and those with the bare buffer. The ratio decreases down to about 0.3 for an albumin concentration of 70 g/L. The time to attain the equilibrium IT decreases from 2 hours to a few minutes, by increasing albumin concentration. The obtained values of the dilational viscoelasticity modulus are increased by the presence of albumin up to values significantly larger than those observed for short chain surfactant molecules.
The observed values of IT in the presence of a common serum protein are compatible with the promotion of droplets formation, which, in addition, are expected to be more stable against coalescence, owing to the larger values of the dilational viscoelasticity modulus. This therefore calls for an increased tendency of the oil to emulsify.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
The IT normalized with the value corresponding to pure silicone oil-aqueous solution as a function of the albumin concentration.
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