Plasma surface fluorination of hydrogel materials-coating stability and in vitro biocompatibility testing

Plasma enhanced chemical vapor deposition has been tested for the formation of hydrophobic perfluorinated coating on the surface of hydrophilic poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) [poly(HEMA-co-MMA)] substrates, used for the fabrication of intraocular lenses (IOLs). The properties of the dry and hydrated surface modified by two plasma techniques, Radio-frequency (RF) and Microwave (MW), were investigated in parallel by contact angle measurements in the dry and hydrated state, X-ray photoelectron spectroscopy, and atomic force microscopy. The coating stability and hydrophobicity were challenged by swelling and sterilizing the samples in water. Investigation of the optical performances of the modified samples was performed by ultraviolet spectroscopy and diopter measurements. Since materials with biomedical application are considered, the performances of their surface in contact with lens epithelial cells were tested at in vitro conditions, and repulsion was not found to be enhanced upon modification. Generally, the results showed poor stability of the coating and bring in question its covalent grafting to the surface.