DMTMM-mediated synthesis of norbornene-modified hyaluronic acid polymers to probe cell-hydrogel interactions

Synthesis of chemically modified hyaluronic acid (HA) polymers has enabled the fabrication of hydrogels, such as norbornene-modified HA (NorHA) hydrogels that can provide tunable mechanical properties. However, current protocols for the synthesis of NorHA polymers rely on the use of dimethyl sulfoxide (DMSO), a solvent that is cost-intensive and requires extensive dialysis to be removed. To address this limitation, we developed an organic solvent-free NorHA synthesis protocol based on the triazine derivative 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) which enables control over the degree of substituted norbornene groups and hydrogel mechanical properties. Our study further demonstrates the incorporation of enzymatically degradable crosslinkers to fabricate NorHA hydrogels as an in vitro platform to tune cell spreading and nascent protein deposition towards their use in tissue engineering and regenerative medicine.