Precise Design of Alginate Hydrogels Crosslinked with Microgels for Diabetic Wound Healing.

Alginate hydrogel has received great attention in diabetic wound healing. However, the limited tunability of the ionic crosslinking method prevents the delicate management of physical properties in response to diverse wound conditions. We addressed this issue by using a microgel particle (fabricated by zinc ions and coordinated through the complex of carboxymethyl chitosan and aldehyde hyaluronic acid) as a novel crosslinker. Then the cation was introduced as a second crosslinker to create a double crosslinked network. The method leads to the precise regulation of the hydrogel characters, including the biodegradation rate and the controlled release rate of the drug. As a result, the optimized hydrogels facilitated the live-cell infiltration in vitro and boosted the tissue regeneration of diabetic wounds in vivo. The results indicated that the addition of the microgel as a new crosslinker created flexibility during the construction of the alginate hydrogel, adapting for diverse applications during diabetic-induced wound therapy.

Zinc ions coordinated carboxymethyl chitosan-hyaluronic acid microgel for pulmonary drug delivery.

Microgel affords a porous and swollen microstructure for the establishment of pulmonary delivery system with sustained released properties. Here, we report a microgel (with the diameter around 4 µm) prepared with a precipitation method, synthesized by coordinating Zn2+ to the Schiff base cross-linked carboxymethyl chitosan and glycol split hyaluronate. The microgel has shown well swollen and pH sensitive behaviors, high safety and biocompatibility in vitro. Besides, the biomaterial could escape from macrophage phagocytosis, a key factor contribute to quick drug clearance in the lung after co-incubated with RAW 264.7 cells. In consist with this, the bovine serum albumin loaded in the microgel showed sustained release behavior in 24 h in vitro; meanwhile, the drug had a retention time up to 36 h in the lung and followed by clearance in ICR mice through pulmonary administration. Thus, our microgel platform provides a promising candidate for pulmonary drug delivery systems with controlled release rate.