Device Design and Diagnostic Imaging of Radiopaque 3D Printed Tissue Engineering Scaffolds

Abstract

3D printed biomaterial implants are revolutionizing personalized medicine for tissue repair, especially in orthopedics. In this study, a radiopaque Bi2O3 doped polycaprolactone (PCL) composite is developed and implemented to enable the use of diagnostic X-ray technologies, especially photon counting X-ray computed tomography (PCCT), for comprehensive in vivo device monitoring. PCL filament with homogeneous Bi2O3 nanoparticle (NP) dispersion (0.8 to 11.7 wt%) are first fabricated. Tissue engineered scaffolds (TES) are then 3D printed with the composite filament, optimizing printing parameters for small feature size and severely overhung geometries. These composite TES are characterized via micro-computed tomography ({micro}CT), tensile testing, and a cytocompatibility study, with Bi2O3 mass fractions as low as 2 wt% providing excellent radiographic distinguishability, improved tensile properties, and equivalent cytocompatibility of neat PCL. The excellent radiographic distinguishability is validated in situ by imaging 4 and 7 wt% TES in a mouse model with {micro}CT, showing excellent agreement with in vitro measurements. Subsequently, CT image-derived swine menisci are 3D printed with composite filament and re-implanted in their corresponding swine legs ex vivo. Re-imaging the swine legs via clinical CT allows facile identification of device location and alignment. Finally, the emergent technology of PCCT unambiguously distinguishes implanted menisci in situ.