3D-printed bionic tracheal stents based on tunable triblock thermoplastic copolyester elastomers for tracheal stenosis.

Poly(ε-caprolactone) (PCL) has attracted significant attention in biomedical applications, including drug delivery, tissue engineering, and biodegradable implants. However, its inherently poor elasticity restricts its applicability in mechanically dynamic tissues and organs. Here, 4-methyl-ε-caprolactone (MCL), a biobased monomer structurally similar to ε-caprolactone (CL), was incorporated to produce poly(ε-caprolactone)-b-poly(4-methyl-ε-caprolactone)-b-poly(ε-caprolactone) (PCL-PMCL-PCL) triblock polymers via sequential ring-opening polymerization. The resulting triblock polymers exhibited tunable elasticity and mechanical properties of thermoplastic elastomers (TPEs) and showed excellent compatibility with 3D printing. Tracheal stents are widely used to provide rapid and effective relief from tracheal stenosis, with silicone and metallic stents being the most common options. However, complications such as mucus plugging and stent migration remain unresolved challenges and their inability to be 3D printed limits personalized treatment. To address these issues, we explored the use of triblock thermoplastic polyester elastomers for tracheal stent fabrication. A bionic tracheal stent featuring cartilage-mimicking surface protuberances to prevent migration was produced using a custom-developed 3D printer. In vitro experiments demonstrated that the stents possessed suitable mechanical strength, elasticity, and anti-migration properties. In vivo, the bionic stents effectively alleviated malignant tracheal stenosis in a rabbit model. Overall, these findings suggest that PCL-PMCL-PCL triblock thermoplastic elastomers hold strong potential for next-generation tracheal stents and may serve as promising biomaterials for broader tissue engineering applications.