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Sienna K. Sun, Jeayoung Jeong, Joseph M. Scalet, and Stevin H. Gehrke

¹Department of Chemical and Petroleum Engineering, University of Kansas

Certain ocular diseases, including aged-related macular degeneration, require repeated drug deliveries via intravitreal injections to the posterior cavity of the eye, an uncomfortable and expensive treatment. This exploration investigates a specific hydrogel’s viability as an alternative to frequent injections by attempting to control the network structure of the hydrogel, pentanoate modified dextran (PDEX). As a biocompatible, degradable, and viscoelastic material, this novel gel was studied to justify whether the thiol-ene “click” chemistry reaction creates more efficient and uniform network structures, allowing better control of properties such as diffusion rates in drug delivery systems. Diffusion tests were performed with vitamin B-12 to quantify the diffusion coefficients of various thiol-ene ratio PDEX gels. Another studied drug-delivery hydrogel, divinyl sulfone dextran (DVS), was synthesized with different DVS crosslink ratios and used to compare network properties with PDEX hydrogels, hypothesizing better network control for the thiol-ene reaction versus the chemically crosslinked DVS-dextran gels. DVS gels were utilized specifically for comparing diffusion coefficients of gels with similar swelling degrees. Additional property tests performed include uniaxial compression to measure mechanical properties and swell testing to measure the water sorption capacity. With these measurable properties, crosslink density was found to quantify the average network mesh size. PDEX hydrogels were successfully synthesized and primarily displayed diffusion trends as predicted, with the optimal controlled thiol-ene crosslinking ratio as 1:1. The structure relationship of the PDEX and DVS gels should be investigated further for potential PDEX application in drug delivery systems.