GelMA Synthesis and Characterization

GelMA was synthesized using a modified published protocol.²⁷ All materials were purchased from Sigma Aldrich (St. Louis, MO) unless otherwise specified. Porcine gelatin was dissolved at 10% w/v in reaction buffer [1.1 M sodium carbonate and 1.1M sodium bicarbonate in deionized water] at 50°C. 1% v/v Methacrylic anhydride was added dropwise and allowed to react while spinning for 3 hours at 50°C. GelMA was precipitated in acetone, then dialyzed at 50°C for 4 days. The dialyzed GelMA was then aliquoted into 50 ml conical tubes, frozen, and lyophilized. The GelMA was stored at −20°C until used.

Degree of modification was measured using TNBS assay (ThermoFisher, Waltham, MA) and confirmed using H-NMR. GelMA was compared against gelatin at 1mg/ml, and absorbance was measured at 335 nm using a Cytation3 plate reader (BioTek, Winooski, VT). For H-NMR, GelMA and gelatin samples were dissolved in deuterium oxide at 50 mg/ml and measured using Bruker Avance III HD nanobay AX-400 (Bruker, Madison, WI). Data was analyzed using TopSpin software (Bruker, Madison, WI).