Functional Enhancement of Guar Gum-Based Hydrogel by Polydopamine and Nanocellulose.

The development of green, biomedical hydrogels using natural polymers is of great significance. From this viewpoint, guar gum (GG) has been widely used for hydrogel preparation; however, its mechanical strength and adhesion often cannot satisfy the biomedical application. Therefore, in the present study, gelatin and a cellulose nanocrystal (CNC) were first applied to overcome the defects of guar gum hydrogel. Dopamine was self-polymerized into polydopamine (PDA) on the gelatin chain at alkaline condition, and gelatin-polydopamine (Gel-PDA) further cross-linked with guar gum and CNC via the borate-didiol bond, intramolecular Schiff base reaction, and Michael addition. CNC not only interacted with guar gum using borate chemistry but also acted as a mechanical reinforcer. The obtained Gel-PDA+GG+CNC hydrogel had an excellent self-healing capacity, injectability, and adhesion due to the catechol groups of PDA. Moreover, dopamine introduction caused a significant increase in the anti-oxidant activity. This hydrogel was cyto- and hemo-compatible, which implies a potential usage in the medical field.