Device Design and Advanced Computed Tomography of 3D Printed Radiopaque Composite Scaffolds and Meniscus.

3D printed biomaterial implants are revolutionizing personalized medicine for tissue repair, especially in orthopedics. In this study, a radiopaque bismuth oxide (BiO) doped polycaprolactone (PCL) composite is developed and implemented to enable the use of diagnostic X-ray technologies, especially spectral photon counting X-ray computed tomography (SPCCT), for comprehensive tissue engineering scaffold (TES) monitoring. PCL filament with homogeneous BiO nanoparticle (NP) dispersion (0.8 to 11.7 wt%) are first fabricated. TES are then 3D printed with the composite filament, optimizing printing parameters for small features and severely overhung geometries. These composite TES are characterized via micro-computed tomography (μCT), tensile testing, and a cytocompatibility study, with 2 wt% BiO NPs providing improved tensile properties, equivalent cytocompatibility to neat PCL, and excellent radiographic distinguishability. Radiographic performance is validated in situ by imaging 4 and 7 wt% BiO doped PCL TES in a mouse model with μCT, showing excellent agreement with in vitro measurements. Subsequently, CT image-derived swine menisci are 3D printed with composite filament and re-implanted in 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 SPCCT unambiguously distinguishes the implanted meniscus in situ via means of color K-edge imaging.