Design, Characterization, and Biocompatibility of\nModular Biopolymer-Based Single- and Double-Cross-Linked Networks\nHydrogels

The synthesis of the modular ketone-rich\ndextrin acetoacetate (DXTAA)\nand its application in the click chemistry-based synthesis of single-cross-linked\nnetwork (SN) and double-cross-linked network (DN) biopolymeric hydrogels\nare reported. DXTAA is obtained in a base-catalyzed transesterification\nreaction between dextrin and <i>tert</i>-butyl acetoacetate.\nDXTAA forms covalently cross-linked SN hydrogels with a hydrazide\nderivative of alginate (Alg-SDH) via hydrazone linkages in aqueous\nsolution without any initiator, heat, or catalyst. The presence of\ncarboxylate groups in Alg-SDH enables the preparation of DN hydrogels\nusing calcium ions as an ionic cross-linker. The swelling ratio and\nthe stability of the hydrogels are shown to be pH-dependent; the DN\nhydrogel exhibits considerably higher stability at pH 7.4 compared\nto the SN hydrogel. Both hydrogels are shown to be noncytotoxic and\nbiocompatible. Thus, DXTAA can be considered a promising cross-linker\nfor the in situ click synthesis of biocompatible gel.