Effect of Electron Beam Sterilization on Three-Dimensional-Printed Polycaprolactone/Beta-Tricalcium Phosphate Scaffolds for Bone Tissue Engineering.

Three-dimensional printing of composite materials such as polycaprolactone/beta-tricalcium phosphate (PCL/-TCP) enables the design and manufacturing of scaffolds with advanced geometries, along with improved physical and biological properties for large bone defect repair. Terminal sterilization of the scaffolds is inevitable for clinical applications. Electron beam (E-beam) is nontoxic, and can be used for sterilizing heat-sensitive scaffolds by the use of high radiation dose in a short period of time. In this article, we assessed the influence of E-beam sterilization on the properties of 3D-printed PCL/-TCP scaffolds, focusing on the key physical and biological properties for bone tissue engineering. More specifically, we characterized the effect of a single-dose E-beam sterilization (25kGy, ISO 11137) on surface morphology, hydrophilicity, degradation, and mechanical properties of the scaffolds as well as in vitro biological responses. The results showed that E-beam irradiation did not alter the surface properties of scaffolds. A 14% increase in initial mechanical stiffness and strength of the scaffolds was observed after E-beam treatment. In addition, the E-beam-treated scaffolds had 25% faster degradation. The PCL chains within the scaffolds had larger polydispersity after the E-beam irradiation that was indicative of a concurrent cross-linking and chain scission. Moreover, in vitro cell studies showed no influence of E-beam sterilization on viability, attachment, proliferation, and osteogenic differentiation of cells seeded on the PCL/-TCP scaffolds.