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

Abstract

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.

Keywords: alginate hydrogel; diabetic wound healing; microgel; scaffold; tissue regeneration.

Figure 1

The scheme of the microgel synthesis.

Figure 2

The scheme of hydrogel preparation.

Figure 3

FT-IR spectra of the microgels and hydrogels.

Figure 4

Characterization of the hydrogels. (a–d) SEM images of the hydrogels of A (a), B (b), C (c), and D (d). (e) The swelling behavior of the hydrogels. (f) Frequency-sweep dynamic rheological profiles of the hydrogels.

Figure 5

Evaluation of drug (BSA as the representative compound) release profiles in different hydrogels in vitro. (The florescence intensity for 100% release is about 600,000).

Figure 6

The degradation profile in vitro and in vivo (Scale bar = 200 μm). (a,b) The hydrogel degradation behaviors in vitro were investigated during a 9-day period. The photographs of the undegraded gel were taken (a) and their weight was measured at fixed intervals (b,c) The biodegradation behaviors in vivo were investigated 20 days after the gels were implanted in the mice.

Figure 7

Images of 3D NIH-3T3 cell cultures in different gels in vitro (72 h). (a) The cells were stained with DAPI (blue) and lysosome tracker (red). (b) The cell count determination in each visual field.

Figure 8

Monitoring the wound-healing process with the hydrogels on a full excision wound of diabetic mice during a 5-day period. (a) Digital images of diabetic wounds at Day 3, 5. (b) Qualification of the wound area in response to the wound therapies (right panel, n = 5) (** p < 0.01, *** p < 0.001). (c) Representative H&E staining of the wound tissues from each group (Day 5). (d) Representative staining of the wound tissues with Masson’s trichrome method.