The molecular structures of GMI, maleimide and thiol hydrogel precursors were confirmed by Proton and Carbon Nuclear Magnetic Resonance ( 1 H and 13 C NMR). 1 H and 13 C NMR spectra were recorded with an Avance Bruker equipped with BBO z-gradient probe. Experimental conditions were as follows: each sample scanned 128 times. The solvents used were (1) DSMO-d6 for GMI and (2) D2O for 4-arm Dextran, Dex-Mal, HA and HA-SH.