Figure 15. Crosslinking via metal-ligand complexation.

a) Schematic representation of biopolymers modified with catechol groups forming metal-ligand complexes with Fe(III). As pH increases, bis- and tris-complexation occurs, resulting in crosslink formation. b) Chitosan (green) is modified with catechol groups and forms a hydrogel metal-ligand complexation with Fe(III). The injectable hydrogel was used as a localized delivery vehicle for multiple chemotherapeutics. An increase in median survival rate was observed in murine lung and breast cancer models upon localized delivery of anticancer drugs from the hydrogel. Adapted with permission from Yavvari, et al.³⁵⁵ Copyright, 2017 American Chemical Society.