Hemoglobin-crosslinked drug-loaded silk fibroin porous scaffold for long-segment tracheal defect repair: An integrated strategy leveraging dynamic mechanical biomimicry and infection control.

The clinical repair of long-segment tracheal defects (LSTDs) remains a formidable challenge, primarily due to the dynamic mechanical mismatch of current implantable substitutes and high rates of postoperative infection. To address these critical hurdles, we have engineered a novel silk fibroin (SF)-based scaffold, designated Hb-SF@LVX, that simultaneously achieves dynamic mechanical biomimicry and robust infection control. By employing a synergistic dual-crosslinking strategy-combining hemoglobin (Hb)-catalyzed chemical crosslinking with low-temperature-induced β-sheet formation-the scaffold exhibits remarkable elasticity and fatigue resistance, closely mimicking the properties of native tracheal tissue. Furthermore, the scaffold was efficiently loaded with levofloxacin (LVX) and demonstrated prolonged, sustained release, conferring potent antibacterial and anti-biofilm efficacy. To replicate the intricate hierarchical architecture of the native trachea, we modularly assembled pre-cultured cartilage rings (CRs) with optimized scaffold rings (SRs), fabricating a biomimetic trachea (BT) with a "CRs-SRs" structure. In situ transplantation in a rabbit LSTD model revealed that the SF-120 BT, carrying an optimal LVX concentration, achieved a survival rate exceeding 75 %. Compared to the control group, it demonstrated substantially improved luminal patency and mechanical performance. Crucially, it successfully suppressed infection, mitigated inflammation, and promoted high-quality regeneration of cartilage, fibrous connective tissue, as well as facilitating epithelialization and vascularization. These comprehensive outcomes culminated in the successful structural and functional reconstruction of the defective trachea. Collectively, this research establishes a new paradigm for the clinical management of LSTDs by integrating adaptable dynamic mechanics, effective infection control, and enhanced tissue regeneration within a single, innovative platform.