Page 39 - Improved endothelialization by silicone surface modification and fluid hydrodynamics modulation- Implications for oxygenator biocompatibility Nasim

and anti-thrombotic functionality. Figure 2 shows a schematic of the reactions of plasma modification and graft polymerization (with AmS or AAc) followed by collagen immobilization on silicone tubes. The abbreviations used for surface- modified silicone tubes are provided in Table 1.
3
Figure 2. Schematic illustration of plasma surface modification, plasma graft polymerization, and collagen immobilization in the lumen of silicone tubes. Peroxide group formation: silicone tubes were exposed to air for 10 min after plasma modification. Carboxyl group formation: plasma surface-modified silicone tubes were immersed in an aqueous solution of AAc followed by plasma graft polymerization on a reabsorbed layer of AAc on silicone. Amine group formation: plasma surface-modified silicone tubes were immersed in an aqueous solution of APTES for aminosilanization followed by submerging in distilled water.
Grafted monomer and immobilized collagen density on surface-modified silicone tubes
The peroxide groups initiated the formation of carboxyl groups by graft polymerization of AAc, or the formation of amine groups by graft polymerization of AmS on the silicone surface. The graft mass density of AAc was much lower than of AmS (AAc: 420±28 μg cm-2; AmS: 987±43 μg cm-2, mean±SD), but since the molecular weight of AAc was also lower than AmS (AAc: 72.06 g mol-1; AmS: 221.37 g mol-1), the graft molar densities weree similar (Table 2). The negatively charged carboxyl groups on AAc Si tubes interacted with the positively charged amine groups on collagen, and the positively charged amine groups on AmS Si
21
2