Enhancing hydrophilicity and protein resistance of silicone hydrogels by plasma induced grafting with hydrophilic polymers

The hydrophilieity of silicone hydrogels used as soft corneal contact lens plays an important role in wearing comfort.In order to enhance hydrophilicity and protein resistance,silicone hydrogel membranes were modified by atmospheric pressure glow discharge plasma(APGDP)induced surface graft polymerization of N-vinyl pyrrolidone(NVP)and poly(oligoethylene glycol methyl ether methacrylate)(PEGMA)in this paper.XPS analysis demonstrated the success of graft polymerization of NVP and PEGMA onto the surface of silicone hydrogel membranes.The hydrophilicity of silicone hydrogels was characterized by the measurement of water contact angle(WCA).The result showed that NVP grafted silicone hydrogel has the WCA of about 68° and PEGMA grafted silicone hydrogel has the lowest WCA of about 62°,while the pristine silicone hydrogel is hydrophobic with the WCA of about 103°.Protein resistance of silicone hydrogels was investigated by the method of bicinchoninic acid assay using bovine serum albumin(BSA)as a model.It's found that the grafted silicone hydrogel has a significant improvement of protein resistance,and PEGMA grafting is more efficient for the reduction of protein adsorption than NVP grafting.The silicone hydrogel membranes grafted with NVP and PEGMA are good candidates of soft corneal contact lenses.