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Hydrogel Network Formation Revised: High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance as a Powerful Tool for Measuring Absolute Hydrogel Cross-Link Efficiencies

Volume 64, Number 10 (Oct. 2010) Page 1176-1180

Van Vlierberghe, Sandra; Fritzinger, Bernd; Martins, José C.; Dubruel, Peter

In the present work, high-resolution magic angle spinning (hr-MAS) NMR spectroscopy is applied as a straightforward nondestructive technique to quantify unreacted methacrylamide functionalities in cross-linked gelatin hydrogels. By adjusting several cross-linking parameters including the ultraviolet (UV) irradiation time and the photo-initiator concentration, the cross-linking degree can be easily varied. Remarkably, under all experimental conditions typically applied for hydrogel development, no more than 40% of the methacrylamide moieties present have reacted. The hr-MAS based approach to determine the cross-linking efficiency is shown to provide an innovative and more convenient alternative to the well-established classical techniques. In addition, the results obtained are in good correlation with mechanical analysis data.