Biomechanical properties of a customizable TPU/PCL blended esophageal stent fabricated by 3D printing

Esophageal stents are used commonly for the clinic's palliative therapy of esophageal cancer. However, commercial esophageal stents are normally manufactured in certain sizes and cannot be personalized according to esophageal geometry of patient. In the present work, we develop a kind of thermoplastic polyurethane (TPU)/Poly-ε-caprolactone (PCL) blended esophageal stent using melt blending method combined with 3D printing technique. The morphology and physicochemical characteristic of the material are investigated via Scanning Electron Microscope (SEM), Differential Scanning Calorimetry (DSC), Thermal Gravity Analysis (TGA) and mechanical tests. Through the modulation of component rate between TPU and PCL based on Fused Deposition Modeling (FDM), the manipulation of mechanical behavior of esophageal stent can achieved. The in vitro degradation experiment is performed in Phosphate Buffer Solution (PBS) and Simulated Gastric Fluid (SGF). Evaluation of the cytotoxicity of blends is accomplished by MTT colorimetric assay. Furthermore, the radial force and the migration resistance force of the stent are explored experimentally, and finite elemental analysis is conducted to investigate the effectiveness and the comfort of the patient after stent implantation. The results show that the TPU/PCL blends exhibit good miscibility, excellent biomechanical properties, and nontoxicity. The mechanical properties and weight of the stent do not change significantly after 8-week in vitro degradation assay. The superior mechanical and biologic features of our proposed 3D-printed TPU/PCL blended stent demonstrate the potential application to the clinical personalized treatment of esophageal strictures.