Synthesis and Characterization of Methacrylated Alginate

Methacrylated alginate (AMA) was synthesized as previously described.^{24 (link), 56 (link)} Briefly, a 2% (w/v) solution of Manugel® GMB (MW≈ 170–240 kDa, FMC Biopolymer) in deionized (DI) water was mixed with a 20-fold molar excess of methacrylic anhydride (Sigma-Aldrich). The solution was maintained at pH 8 using 5 N sodium hydroxide (Fisher) for 24 hours. Purification was performed via dialysis (MWCO=6–8 kDa) against DI water for 5-days, and lyophilized to yield a dry product. A 1% (w/v) AMA was prepared in deuterium oxide (D₂O, Acros Organics) and subsequently analyzed using ¹H-NMR spectroscopy (Bruker AVANCE III 500 MHz high-field NMR spectrometer), for 64 scans at 20 Hz. The degree of methacrylation (DOM) was established through integration of the peaks associated with methacrylate (6.24, 5.78 ppm) and alginate methyl resonances (1.96 ppm), and calculation of the ratios between.^{29 (link), 56 (link), 58}