Chitosan catechol-tannic acid composite hydrogel and cryogel with antimicrobial and hemostatic properties.

Hydrogels containing catechol group have received attention in the biomedical field due to their robust adhesive/cohesive capabilities, biocompatibility, and hemostatic abilities. Catechol-functionalized chitosan holds promise for preparing self-assembly hydrogels. However, issues of inefficient gelation and instability still persist in these hydrogels. In the current study, we synthesized chitosan catechol (CC) of high catechol substitution (∼28 %) and combined CC with tannic acid (TA, which also contains catechol) to form self-healing CC-TA hydrogels. The catechol-enriched CC-TA composite hydrogels showed rapid gelation and mechanical reinforcement (shear modulus ∼110 Pa). In situ coherent small-angle X-ray scattering (SAXS) coupled with rheometry revealed a morphological feature of mesoscale clusters (∼20 nm) within CC-TA hydrogel. The clusters underwent dynamic destruction under large-amplitude oscillatory shear, corresponding with the strain-dependent and self-healing behavior of the CC-TA hydrogel. The composite hydrogel had osmotic-responsive and notable adhesive properties. Meanwhile, CC-TA composite cryogel prepared simply through freeze-thawing procedures exhibited distinctive macroporous structure (∼200 μm), high water swelling ratio (∼7000 %), and favorable compressive modulus (∼8 kPa). The sponge-like cryogel was fabricated into swabs, demonstrating hemostatic capacity. The CC-TA composites, in both hydrogel and cryogel forms, possessed ROS scavenging ability, antimicrobial activity, and cell compatibility with potentials in biological applications.