The synthesis of the modular ketone-rich
dextrin acetoacetate (DXTAA)
and its application in the click chemistry-based synthesis of single-cross-linked
network (SN) and double-cross-linked network (DN) biopolymeric hydrogels
are reported. DXTAA is obtained in a base-catalyzed transesterification
reaction between dextrin and tert-butyl acetoacetate.
DXTAA forms covalently cross-linked SN hydrogels with a hydrazide
derivative of alginate (Alg-SDH) via hydrazone linkages in aqueous
solution without any initiator, heat, or catalyst. The presence of
carboxylate groups in Alg-SDH enables the preparation of DN hydrogels
using calcium ions as an ionic cross-linker. The swelling ratio and
the stability of the hydrogels are shown to be pH-dependent; the DN
hydrogel exhibits considerably higher stability at pH 7.4 compared
to the SN hydrogel. Both hydrogels are shown to be noncytotoxic and
biocompatible. Thus, DXTAA can be considered a promising cross-linker
for the in situ click synthesis of biocompatible gel.