Preparation of contact lens materials

Silicone contact lens hydrogels were prepared under nitrogen by the photocrosslinking of 2-hydroethylmethacrylate (HEMA), silicone-containing monomers of 3-(trimethoxysilyl)propyl methacrylate, 3-[tris(trimethylsiloxy)silyl]propyl methacrylate, and a cross-linker of ethyleneglycol dimethacrylate (EGDMA) for 15 min using a photoinitiator of Darocur TPO, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. As a control, PHEMA contact lens hydrogels were prepared by mixing HEMA and EGDMA with the photoinitiator. To form a contact lens shape, the precursor solution was loaded on a polypyrrole mold under ultraviolet (UV) light at a wavelength of 254 nm for 8 min. Silicone and PHEMA hydrogel contact lenses were detached from the mold and surface-treated under oxygen plasma (OptiGlow ACE, Glow Research). The prepared contact lens was completely submerged in PBS at 37°C for a day before use.