Halicin-loaded injectable hyaluronic acid hydrogel for ferroptosis-driven osteosarcoma therapy via Fe²⁺ accumulation

Osteosarcoma (OS) is the most common primary malignant bone tumor in adolescents, featuring aggressive tumor growth and early metastasis. Current treatments, including chemotherapy and surgery, are often limited by chemoresistance and postoperative infections. Ferroptosis has emerged as a strategy to overcome chemoresistance, as it is intrinsically iron-dependent, whereas OS often exhibits dysregulated iron metabolism. Halicin, a broad-spectrum antimicrobial known to regulate iron metabolism in bacteria, was found to be a ferroptosis inducer for OS in this study. However, its therapeutic efficacy is likely hampered by rapid systemic clearance and poor tumor retention. Accordingly, we developed Halicin@Gel, an injectable hyaluronic acid hydrogel designed for localized and prolonged release. The structure, injectability, drug release behavior, biocompatibility, antibacterial activity, and antitumor efficacy of this system were characterized and evaluated in vitro and in vivo. Halicin@Gel exhibited excellent antibacterial activity and significantly inhibited OS cell proliferation and migration in vitro. Mechanistically, Halicin@Gel increased intracellular ROS levels and was associated with p38 MAPK activation, as well as ferroptosis- and apoptosis-related changes. In vivo, Halicin@Gel significantly inhibited tumor growth with minimal systemic toxicity, confirming its therapeutic potential. Thus, these findings support Halicin@Gel as a promising localized therapeutic platform with combined antitumor and antibacterial functions for OS treatment.