A Polyphenol–Metal Network of Propyl Gallate Gallium/Hafnium Oxide on Polyimide Fibers for Facilitating Ligament–Bone Healing

The development of an artificial ligament for promoting ligament–bone healing in anterior cruciate ligament (ACL) reconstruction still faces enormous challenges. Herein, a polyphenol–metal network (PMN) composed of propyl gallate (PG)-gallium (Ga) and -hafnium oxide (HfO₂) is deposited on polyimide fiber (PIF) woven fabric (PGPH) for artificial ligament application. Compared with PIF, the surface properties (e.g., hydrophilicity) of PMN of PGPH significantly improve. The in vitro cell experiments confirm that PGPH remarkably facilitates proliferation and osteoblastic differentiation due to the synergistic effects of enhanced surface properties and the sustained release of Hf ions. Moreover, PGPH inhibits M1 macrophage polarization, thereby reducing the production of pro-inflammatory cytokines while improving anti-inflammatory cytokines secretion by favoring M2 macrophage polarization, displaying anti-inflammatory effects due to the slow release of PG. Compared with PIF, PGPH exhibits adequate antibacterial activity in vitro and effectively prevents bacterial infection in vivo because of the sustained release of Ga ions, which damages the bacterial membrane and leads to the leakage of cell components (such as proteins). The in vivo experiments reveal that PGPH obviously inhibits fibrous encapsulation formation while promoting bone regeneration for ligament–bone healing. In short, PGPH creates a favorable microenvironment for enhancing M2 macrophage polarization and osteoblastic differentiation, which facilitates ligament–bone healing, thereby exhibiting enormous promise for ACL restoration.

Graphical Abstract