Surface modification of POSS-nanocomposite biomaterials using reactive oxygen plasma treatment for cardiovascular surgical implant applications

In this study, central composite design (CCD) was used to develop predictive models to optimize operating conditions of plasma surface modification. It was concluded that out of the two process variables, power and duration of plasma exposure, the latter was significantly affecting the surface energy (gamma(s)), chemistry, and topography of polyhedral oligomeric silsesquioxane poly(carbonate-urea)urethane (POSS-PCU) films. On the basis of experimental data, CCD was used to model the gamma(s) using a quadratic modeling of the process variables to achieve optimum surface energy to improve the interaction between endothelial cells (ECs). It was found that optimal water theta for EC adhesion and retention, which was reported 55 degrees from supporting literature (equivalent to gamma(s) = 51 mN/m), was easily achievable using the following experimental conditions: (1) power output at 30 W for 75 Sec, (2) 90 W for 40 Sec, and (3) 90 W for 55 Sec in oxygen. In vitro cell culture and metabolic activity studies on optimized films [as in (1)] demonstrate increased adhesion, coverage, and growth of human umbilical vein endothelial cells that were confluent over a shorter time period (< 24 H) than controls. Such materials enhanced the EC response and promoted endothelialization on optimized films, thus demonstrating their use as bypass graft materials. (C) 2011 International Union of Biochemistry and Molecular Biology, Inc. Volume 58, Number 3, May/June 2011, Pages147-161. E-mail: b.cousins@medsch.ucl.ac.uk