Chemical cross-linking gelatin with natural phenolic compounds as studied by high-resolution NMR spectroscopy

Xiaoqing Zhang, My Dieu Do, Philip Casey, Adrian Sulistio, Greg Qiao, Leif Lundin, Peter Lillford, Shansha Kosaraju

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137 Citations (Scopus)


Cross-linking gelatin with natural phenolic compound caffeic acid (CA) or tannic acid (TA) above pH 9 resulted in formation of insoluble hydrogels. The cross-linking reactivity was controlled by variation of pH, the concentration of the gelatin solution, or the amount of CA or TA used in the reaction. The cross-linking chemistry was studied by high-resolution NMR technique in both solution and solid state via investigation on small molecular model systems or using 13C enriched caffeic acid (LCA) in the reaction with gelatin. Direct evidence was obtained to confirm the chemical reactions occurring between the phenolic reactive sites of the phenolic compounds and the amino groups in gelatin to form C-N covalent bonds as cross-linking linkages in gelatin matrix. The cross-linked network was homogeneous on a scale of 2-3 nm. The cross-linking resulted in a significant decrease in the molecular mobility of the hydrogels, while the modulus of the films remained at high values at high temperatures.

Original languageEnglish
Pages (from-to)1125-1132
Number of pages8
Issue number4
Publication statusPublished - 12 Apr 2010
Externally publishedYes

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