Tannin-bridged magnetic responsive multifunctional hydrogel for enhanced wound healing by mechanical stimulation-induced early vascularization.

Wound healing is a complex process. Wound-repair materials require multiple functionalities, such as anti-inflammatory, antibacterial, angiogenesis, pro-proliferation, and remodeling. To achieve rapid tissue regeneration, magnetic field-assisted therapy has become a promising means. In this study, a homogeneous magnetic responsive nanocomposite hydrogel with enhanced mechanical properties was obtained through a tannin (TA)-assisted bridge between magneto-deformable cobalt ferrite nanoparticles (CFO NPs) and polyvinyl alcohol (PVA) matrix. In the presence of an external static magnetic field (SMF), the TA bridge could efficiently transmit magnetically actuated deformation to the PVA, which originated from the CFO NPs, generating a larger topographic change on the surface. The change of topography provided a mechanical cue to increase cell adhesion and proliferation. Moreover, due to the synergistic effects of TA modification and CFO NPs, the obtained magnetic responsive hydrogel exhibited considerable antibacterial activity. Furthermore, the results of in vivo study confirmed the anti-inflammatory properties of the TA-CFO/PVA hydrogel. More importantly, the TA-CFO/PVA hydrogel accelerated wound healing under a SMF, which contributed to the early vascularization induced by mechanical stimuli generated from the TA-CFO/PVA nanocomposite hydrogel. As a proof-of-concept, we provided an optimizing strategy for magneto-controlled skin tissue regeneration, which may have important guiding significance for the clinical application of magnetic field-assisted therapy.