Abstract
Silicone rubber (SR) membranes were modified via plasma-induced graft copolymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) to enhance the biocompatibility. The chemical composition of the surface of the pMPC-grafted SR was analyzed using ATR-FTIR and ESCA, while the surface morphologies and cross-sections of the membranes were examined by SEM.The SR surface appeared homogeneously grafted with pMPC. Contact angle analysis revealed that the pMPC-grafted SR films organized more hydrophilic surfaces than the controlled film. The contact angle decreased from 100 degrees to around 20 degrees at last. Tensile tests revealed that the plasma-induced polymerization of pMPC could modify the surface properties of SR without altering its bulk mechanical properties.Furthermore, in vitro tests were performed to evaluate the biocompatibility of the modified SR membranes. In contrast to the controlled SR membrane, the surfaces of the pMPC-grafted SR membranes tend to effectively reduce the adsorption of bovine serum albumin (BSA), suppress the adhesion of platelets and blood cells, and effectively suppress the attachment and proliferation of fibroblasts when the grafted pMPC reaches a certain value (P/Si = 0.034).After then, the pMPC-grafted SR membranes were implanted into the sclera using Zelanian rabbits as animal model. Pathological studies showed a large number of migratory cells tended to embrace the controlled SR membrane. After implanted for three weeks, there was a thick layer of fibrotic tissue ensheathing the Ar-plasma-treated SR membrane, and the thickness of which was about 12.5μm.Marvelously, there was little inflammatory lymphocytes or white blood cells gathering around the pMPC-grafted SR (P/Si = 0.035, 0.067 and 0.096) membranes. The thickness of fibrotic capsule surrounding the pMPC-grafted SR(P/Si = 0.035 and 0.067) membranes was reduced to about 2.6μm, and inapparent fibrosis was observed around the pMPC-grafted SR(P/Si = 0.096) membrane in three weeks. The interaction between the surface of the pMPC-grafted SR and the tissue of the subconjunctiva remained gentle in six weeks. The pMPC-grafted SR (P/Si >0.035) materials are highly promising for the drainage devices in the treatment of glaucoma.