2.2. Methacrylation of Chondroitin Sulfate and Hyaluronic Acid

Methacrylated chondroitin sulfate (MeCS) and hyaluronic acid (MeHA) were prepared by reacting the hydroxyl functional groups of both CS and HA with GMA, as described previously [22]. Briefly, CS was dissolved in phosphate-buffered saline (PBS) at a final concentration of 10% w/v and 10% v/v GMA was added dropwise to the mixture. Next, the reaction mixture was allowed to react for 11 days under vigorous stirring. The resulting solution was dialyzed in deionized (DI) water for 2 days using a dialysis membrane (MCO, ~1000 Da) and then lyophilized. Similarly, for MeHA, HA was dissolved in PBS at a final concentration of 1% w/v, and 2% v/v GMA was added dropwise. The reaction mixture was allowed to react for 8 days under vigorous stirring, dialyzed, and lyophilized. The ¹H nuclear magnetic resonance (NMR) spectra for MeCS and MeHA were obtained using a Bruker 400 MHz spectrometer (Supplementary Figure S1 in Supplementary Materials). Both MeCS and MeHA were stored at −20 °C until future use.