Antioxidant Activity of Hydrogel Lens Applied with Gallic Acid

Purpose : To produce a hydrogel contact lens (Hy) having an antioxidant functionality, a method of applying gallic acid (GA) into Hy without phase separation is studied, and the effects on the physical properties and antioxidant activity of the lens applied with gallic acid are investigated. Methods : The Hy were produced by a thermal polymerization method in a lab. Chitosan (Cs) used for bonding with GA was used in two types with molecular weights of 100~300 kDa(CL), 600~800 kDa(CH), and was added to Hy by an IPN (Interpenetrating polymer network) method. The optical transmittance was measured in a wavelength range of 300 to 800 nm, and the water content was measured by a gravimetric method. The binding of GA was confirmed by an amide bond formation using FT-IR, and the amount of the GA was quantified by the UV absorbance measured at 298 nm. The antioxidant activities of the lens were assessed using DPPH(2,2-diphenyl- 1-picrylhydrazyl) radical scavenging assay. Results : The optical transmittance was 95% in Hy, 91% in Hy-CL-GA and Hy-CH-GA. The water content is 50.5±1.2%, 52.4±0.7% and 55.6±0.6% in Hy, Hy-CL-GA and Hy-CH-GA, respectively. The amount of GA bound to lens was 0.30 mmol/cm2 in Hy-CL-GA and 0.37 mmol/cm2 in Hy-CH-GA. The antioxidant effect was 48.23% in Hy-CL-GA and 58.32% in Hy-CH-GA, which showed high antioxidant activity in both lenses with GA. Conclusion : The functional hydrogel contact lenses with high optical transmittance, water content and antioxidant activity were produced using Cs and GA. As the amount of GA bound to the lens increased, the water content and antioxidant activity increased. By suggesting the method employing polysaccharides and polyphenols to the contact lens, it is expected to contribute to the production of multifunctional contact lenses with protein inhibition, improved wettability, and antioxidant activity.