Page 41 - Improved endothelialization by silicone surface modification and fluid hydrodynamics modulation- Implications for oxygenator biocompatibility Nasim

Mechanical properties of surface-modified silicone tubes
The ultimate tensile strength of AmS Si tubes was 1.8-fold higher than that of Si, 2- fold higher than that of PSM Si, and 1.6-fold higher than that of AAc Si tubes, showing that silicone tubes stiffened after surface modification with amine groups (Figure 3a). The percent elongation at break was more than 100% for Si, PSM Si, AAc Si, and AmS Si tubes, with no statistically significant differences observed between tubes (Figure 3b). The ultimate tensile strength and elongation at break of PSM Si and AAc Si tubes were similar to Si tubes.
Wettability of surface-modified silicone tubes
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Figure 3. Mechanical properties of unmodified and surface-modified silicone tubes. (a) Ultimate tensile strength, (b) Elongation-at-break of silicone tubes. n=3. The ultimate tensile strength of AmS Si tubes was 1.8-fold higher than Si tubes, showing that silicone tubes became more stiff after surface modification with amine groups. Elongation-at- break of different surface-modified tubes was not statistically different. Si, silicone; PSM Si, plasma surface-modified silicone; AAc Si, acrylic acid-grafted silicone; AmS Si, aminosilane-grafted silicone. *Significant effect of surface modification, p <0.05.
To assess the hydrophilicity of different surface-modified silicone tubes, the water contact angles were measured by the sessile drop method (Table 3). We found that the water contact angles decreased after plasma surface modification and monomer grafting on silicone tubes (Si: 102±4o; PSM Si: 38±3o, AAc Si: 42±2o, and AmS Si: 49±3o), while the amount of water contact angles were not significantly different (p>0.05) for all surface-modified silicone tubes. Collagen addition slightly
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