A non-swellable, anisotropic hydrogel patch with superior mechanical stability for internal anti-adhesion via physical barrier and inflammation regulation.

Tension-free repair operation in clinic needs an implantable mesh to repair the internal soft-tissue defect. However, the clinical patches fail to simultaneously achieve anti-adhesion, anti-deformation and tissue pro-healing. Herein, a high-performance anti-adhesion hydrogel patch is synthesized by one-step of directed freeze-casting technique via utilizing the FDA-approved poly (vinyl alcohol) (PVA) and carboxymethylcellulose nanofibril (CNF) as the network backbone without any chemical crosslinker. This fully physical crosslinked hydrogel exhibits remarkable mechanical performance because of the highly oriented microstructure and multiple hydrogen bonding, including the matching mechanical property with soft tissue, anti-tearing capability, the great 99 % retention of tensile stress and higher toughness after soaking at PBS for 7 days. And the extremely low swelling ratio of 5.9 % in PBS and combining the higher water-content is superior to other reported anti-swelling hydrogel. Importantly, besides as a robust physical barrier of this hydrogel patch, it also displays the excellent inflammatory regulation via capturing the positively charged proinflammatory cytokines because of the incorporation of the negatively charged CNF, synergistically promoting the remarkable anti-adhesion and tissue pro-healing efficiency. By integrating the anti-adhesion, tissue pro-healing, long-lasting anti-deformation in vivo and excellent bio-compatibility, this hydrogel provides a great candidate of anti-adhesion patch for tension-free repair operations.