Thromboresistance of Polyurethanes Modified with PEO-Silane Amphiphiles.

Surface-induced thrombosis is problematic in blood-contacting devices composed of silicones or polyurethanes (PUs). Poly(ethylene oxide)-silane amphiphiles (PEO-SA) are previously shown effective as surface modifying additives (SMAs) in silicones for enhanced thromboresistance. This study investigates PEO-SAs as SMAs in a PU at various concentrations: 5, 10, 25, 50, and 100 µmol g-1 PU. PEO-SA modified PUs are evaluated for their mechanical properties, water-driven surface restructuring, and adhesion resistance against a human fibrinogen (HF) solution as well as whole human blood. Stability is assessed by monitoring hydrophilicity, water uptake, and mass loss following air- or aqueous-conditioning. PEO-SA modified PUs do not demonstrate plasticization, as evidenced by minimal changes in glass transition temperature, modulus, tensile strength, and percent strain at break. These also show a concentration-dependent increase in hydrophilicity that is sustained following air- and aqueous-conditioning for concentrations ≥25 µmol g-1 . Additionally, water uptake and mass loss are minimal at all concentrations. Although protein resistance is not enhanced versus an HF solution, PEO-SA modified PUs have significantly reduced protein adsorption and platelet adhesion from human blood at concentrations ≥10 µmol g-1 . Overall, this study demonstrates the versatility of PEO-SAs as SMAs in PU, which leads to enhanced and sustained hydrophilicity as well as thromboresistance.

Thromboresistance of Silicones Modified with PEO-Silane Amphiphiles.

The antifouling properties of poly(ethylene oxide) (PEO)-silane amphiphiles as surface-modifying additives (SMAs) in a condensation cure silicone have been previously demonstrated against simple protein solutions. Comprising an oligo(dimethylsiloxane) tether (m = 13 or 30) and PEO segment (n = 8), sustained protein resistance was achieved even in the absence of a cross-linkable triethoxysilane group, particularly when comprising the longer tether. To probe their potential for thromboresistance, PEO-silane amphiphile SMAs were used to bulk-modify silicones and evaluated for adhesion resistance against whole human blood under both static and dynamic conditions. Both a cross-linkable (XL diblock, m = 13) and a non-cross-linkable (Diblock, m = 30) SMA were evaluated at various concentrations (5-50 µmol SMA/g silicone) in a condensation cure silicone. Under static conditions, silicones modified with either SMA at concentrations of 10 µmol/g or greater were effective in reducing adhesion of human fibrinogen and platelets. Dynamic testing further showed that modified silicones were able to reduce protein adsorption and thrombus formation. This occurred at 5 and 10 µmol/g for silicones modified with XL diblock, m = 13 and Diblock, m = 30 SMAs, respectively. Combined, these results indicate the effectiveness of PEO-silane amphiphiles as SMAs in silicone for improved thromboresistance.