Synthesis and characterization of acrylamide/N-vinylpyrrolidone copolymer with pendent thiol groups for ophthalmic applications

Injectable acrylamide/N-vinylpyrrolidinone copolymers with pendent thiol groups were prepared by a radical polymerization and reductive dissolution reaction. The solution of copolymers was re-gelled through oxidation in air or the thiol-disulfide exchange reaction. The re-gelation time could be adjusted from several minutes to several hours by changing the amount of the disulfide exchange reagent. The re-gelled hydrogels possessed high transmittance in the visible region but could block out some of the ultraviolet radiation. Their refractive indexes ranged from 1.34 to 1.35, and their equilibrium water contents were over 95.0%. The morphologies of the hydrogels were analyzed and the porous structure, with pore sizes of 50-300 microm, was noted. The cytotoxicities of the hydrogels were clearly reduced compared with previous results. The experimental results indicated that the injectable copolymers could be used as an artificial vitreous substance or as a scaffold for lens regeneration.