α-Linolenic Acid-Modified Collagen for Surgical Sutures: Water-Resistant, Anti-inflammatory, and Antibacterial

To address the limitations of pure collagen wet-spun sutures, including poor water resistance and the absence of biological functions such as anti-inflammatory and antibacterial properties, this study introduced α-linolenic acid (ALA), an unsaturated fatty acid, to modify collagen-based sutures prepared via wet spinning, thereby developing a novel absorbable α‑linolenic acid‑modified collagen suture (Col-ALA). The microtopography, mechanical properties, anti-inflammatory and antibacterial activities, and absorbability of the suture were systematically evaluated using scanning electron microscopy, energy-dispersive spectroscopy, mechanical property testing, bacterial coculture assays, inflammatory factor detection, and in vitro degradation experiments. The results demonstrated that α-linolenic acid was successfully grafted onto collagen molecules, without compromising the mechanical properties of the collagen suture. The modification dramatically enhanced water resistance, reducing swelling to 1/10 and preserving near‑full wet strength, whereas unmodified sutures (Col) retained only 20% of their dry strength in the wet state. The Col-ALA suture exhibited an inhibition rate exceeding 90% against Staphylococcus aureus and possessed certain anti-inflammatory effects. The levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were decreased by 20% and 38%, respectively, compared with the unmodified sutures. Under the condition of 1 U/mL collagenase, the suture achieved 90% degradation within 10 days, showing excellent absorbability. Overall, the unsaturated fatty acid-modified collagen-based absorbable suture prepared in this study exhibits excellent comprehensive performance, offering new insights and an experimental basis for the research, development, and clinical application of absorbable sutures.