Highly hydrophilic and antibiofouling surface of zwitterionic polymer immobilized on polydimethylsiloxane by initiator-free atmospheric plasma-induced polymerization

In this study, we have successfully grafted zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer brushes (5-8 nm) on the silicone (polydimethylsiloxane, PDMS)-based contact lenses using initiatorfree and atmospheric plasma-induced polymerization. Varied atmospheric plasmas (O-2, N-2 and Ar gas) were employed in the process of the polymerization of the zwitterionic polymer brushes on the silicone surfaces without the addition of any initiators. The morphology and characterization of the zwitterionic MPC-immobilized films were investigated using atomic force microscopy, contact angle (CA) measurements and X-ray photoelectron spectroscopy. MPC immobilizations will significantly improve the hydrophilicity of silicone contact lenses, and the CA of the MPC modified-silicone contact lenses will decrease to 50 degrees-60 degrees, compared with that of the pristine ones (CA: similar to 90 degrees). Furthermore, the MPC modifications exhibit an anti-fouling capability (25-30% decrease of protein adsorption), which can avoid protein (fibrinogen and human serum bovine) adhesion that would contaminate the contact lenses. It maintains the great oxygen permeability (103 +/- 5 Dk) and transmittance (T%) is still transparent and colorless after MPC grafted on the PDMS contact lens. Therefore, the immobilization of the MPC polymer brushes by atmospheric plasma-induced polymerization would be a rapid method to improve the hydrophilicity and enhance the anti-fouling capability of silicone based-contact lenses.