POLYPROPYLENE AND GLASS FIBER COMPOSITE EXTRUSION FOR ADDITIVE BIOFABRICATION OF BONE TISSUE SCAFFOLDS WITH COMPLEX MICROSTRUCTURES

Osseous fractures account for 16% of all musculoskeletal injuries in the U.S. annually. Various tissue engineering methods have emerged for bone repair, including additive biomanufacturing techniques like extrusion-based bioprinting. Despite technological and scientific advances in bone tissue engineering, it has remained unknown how the complex rheological dynamics of composite material deposition affect the functional properties of fabricated bone scaffolds. The goal of this work is to fabricate mechanically robust, dimensionally accurate, and biocompatible tissue scaffolds for treatment of bone fractures. The objectives of the work are to investigate the influence of (i) single-screw filament extrusion temperature and (ii) internal scaffold microstructures, on the physical and mechanical properties of bone scaffolds, fabricated using fused deposition modeling (FDM). Uniform monofilaments of polypropylene (PP) and glass fibers (GF) were extruded at temperatures of 185 degrees C, 210 degrees C, and 235 degrees C, then used to fabricate porous bone scaffolds via FDM. Also, four scaffolds with bone-like microstructures were designed, based on novel mathematical formulations of triply periodic minimal surfaces (TPMS). The physical and mechanical properties of these scaffolds were characterized to identify optimal fabrication and design parameters. Among the four TPMS designs constructed, Design #2 exhibited the highest compression modulus, attributed to its compact microstructure. Besides, extrusion temperatures of 210 degrees C and 235 degrees C had similar effects on scaffold properties compared to 185 degrees C. These findings contribute to the development of clinically viable bone scaffolds and future advancements in regenerative medicine.