HR-MAS NMR SPECTROSCOPY AS EFFICIENT TOOL TO CHARACTERIZE CROSSLINKED HYDROGELS

Objectives: In the present work, high-resolution magic angle spinning (hr-MAS) NMR spectroscopy is applied as a straightforward non-destructive technique to quantify unreacted methacrylamide functionalities in cross-linked gelatin hydrogels. Methods: 10 w/v% cross-linked methacrylamide-modified gelatin (gel-MOD) hydrogel films were prepared and lyophillsed, followed by resuspension in D sub(2)O. The effect of the photo-initiator concentration (Irgacure 2959, 0.5-10 mol%) and the applied UV irradiation time (5-30 minutes) on the consumption of methacrylamide moieties was evaluated using hr-MAS NMR spectroscopy. Results: The results (data not shown) indicate that a critical amount of 2 mol% photo-initiator is required to obtain a significant amount of methacrylamide-crosslinking. Upon increasing either the photo-initiator concentration (2-10 mol%) or the UV irradiation time (5-60 min), the percentage of reacted methacrylamides increased significantly (P