Influence of the degree of methacrylation on hyaluronic acid hydrogels properties

The properties of hyaluronic acid (HA) hydrogels having a broad range of methacrylation are presented. Increasing solubility of glycidyl methacrylate (GM) in a co-solvent mixture during the methacrylation of HA with GM was shown to produce photopolymerizable HAGM conjugates with various degree of methacrylation (DM) ranging from 14% up to 90%. Aqueous solutions of HAGM macromonomers were photocross-linked to yield hydrogels with nearly full vinyl group conversions after 10 min exposure under ultraviolet light (UV). Hydrogels were characterized by uniaxial compression and volumetric swelling measurements. Keeping the DM constant, the shear modulus was varied from 16 kPa up to 73 kPa by varying the macromonomer concentration. However, at a given macromonomer concentration while varying the DM, similarly the shear modulus varied from 22 kPa up to 65 kPa. Preliminary in-vitro cell culture studies showed that GRGDS modified HAGM hydrogels promoted similarly cell interaction at both low and high DMs, 32% and 60%, respectively. Densely cross-linked hydrogels with a high DM have been shown to be more mechanically robust while maintaining cytocompability and cell adhesion.