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P. D. Hamilton, H. Du, N. Ravi; Biocompatibility of Modified Gellan and Poly(methacryamide) Formulations for Use in Ophthalmic Hydrogel Substitutes. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3594. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
There is a continuing need for better artificial substitutes for vitreous, and accommodative intra-ocular lens materials. This work is an extension of our developing materials that employ disulfide reversible cross-linkers, allowing the resultant copolymers to be reduced, dissolved, and re-gelled in situ.
Gelzan (Sigma, St. Louis), a deacylated form of gellan, was modified with the incorporation of disulfide cross-linkers. Copolymer hydrogels with the methacryl molar formulations of 78% methacrylamide, 20% sodium methacrylate, and 2% bismethacryloyl cystamine were synthesized as described by Hamilton et al., Polym Mater Sci Eng, 101:293, 2009. Polymers were tested for biocompatibility employing thiazylol blue (MTT) in tissue culture using ARPE-19, human retinal epithelial cells from ATCC. There were two Gelzan preparations, with 9% (low) and 21% (high) -SH groups/saccharide unit of Gelzan. These preparations formed gels at 2 mg/mL in PBS. There were also two preparations of copolymer. These preparations formed gels at 12 mg/mL. Lot 1 was washed with acetone while Lot 2 was washed with ethanol, for the purpose of removing unincorporated organics.
Graphs from the biocompatibility experiment are shown in the figure.
Gelzan forms transparent ionic gels that are highly elastic. The incorporation of an S-S cross-linker prevents the dissolution of these gels in the absence of ions, and makes them more permanent. The high level of S-S incorporation had a negative effect on cell morphology and cell growth. The formulation of methacrylamide copolymers tested results in a highly transparent viscoelastic gel. From these results, acetone washing gave a better end product than washing with ethanol. Morphology of the ARPE 19 cells in the presence of the low SH Gelzan and copolymer Lot 1 appeared relatively normal.
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