Design and mechanical characterization of solid and highly porous 3D printed poly(propylene fumarate) scaffolds

The primary goal of tissue engineering is to repair a defect by encouraging new tissue growth and remodeling of that tissue within a biodegradable scaffold. The scaffold is the centerpiece of tissue engineering efforts, and its design and properties are of paramount importance. The architecture of the scaffold will directly impact its mechanical strength, degradation characteristics, and capacity to guide neotissues into the defect. Scaffold porosity is frequently used as a solitary description of architecture, while feature dimensions such as strut size and pore size are largely ignored. It is well known that pore size and shape influence tissue regeneration while strut size (i.e., wall thickness) dramatically affect mechanical strength and resorption kinetics. In this work, we propose a methodology that places special emphasis on feature dimensions using a mathematical approximation of Schoen’s gyroid, a triply periodic minimal surface, as the foundation for pore architecture. By modulating the gyroid and making virtual measurements of the resulting structures, we establish important relationships between feature dimensions and the governing equation. Using this foundation, scaffolds with gyroid-type porosity were designed and 3D printed out of a bioresorbable poly(propylene fumarate)-based resin. Unconfined compression testing was conducted on fully dense parts, as well parts with designed porosity, to establish a baseline for mechanical properties. Orientation-based mechanical anisotropy was seen in these 3D printed porous specimens. Finally, we demonstrate how such architectures can be embedded into anatomical shapes.

Duke Scholars

Author Matthew L Becker Chemistry