Fabrication and Characterization of Poly(Propylene Fumarate) Scaffolds with Controlled Pore Structures Using 3-Dimensional Printing and Injection Molding

Abstract

Poly(propylene fumarate) (PPF) is an injectable, biodegradable polymer that has been used for fabricating preformed scaffolds in tissue engineering applications because of in situ crosslinking characteristics. Aiming for understanding the effects of pore structure parameters on bone tissue ingrowth, 3-dimensional (3D) PPF scaffolds with controlled pore architecture have been produced in this study from computer-aided design (CAD) models. We have created original scaffold models with 3 pore sizes (300, 600, and 900 lm) and randomly closed 0%, 10%, 20%, or 30% of total pores from the original models in 3 planes. PPF scaffolds were fabricated by a series steps involving 3D printing of support/build constructs, dissolving build materials, injecting PPF, and dissolving support materials. To investigate the effects of controlled pore size and interconnectivity on scaffolds, we compared the porosities between the models and PPF scaffolds fabricated thereby, examined pore morphologies in surface and cross-section using scanning electron microscopy, and measured permeability using the falling head conductivity test. The thermal properties of the resulting scaffolds as well as uncrosslinked PPF were determined by differential scanning calorimetry and thermogravimetric analysis. Average pore sizes and pore shapes of PPF scaffolds with 600-and 900-lm pores were similar to those of CAD models, but they depended on directions in those with 300-lm pores. Porosity and permeability of PPF scaffolds decreased as the number of closed pores in original models increased, particularly when the pore size was 300 lm as the result of low porosity and pore occlusion. These results show that 3D printing and injection molding technique can be applied to crosslinkable polymers to fabricate 3D porous scaffolds with controlled pore structures, porosity, and permeability using their CAD models.

Extrusion-based 3D printing of poly(propylene fumarate) scaffolds with hydroxyapatite gradients

“…In both scaffolds with and without SDS, we found that each layer contained continuous fibers and fully interconnected pores. Pore sizes were between 0.600–0.800 mm, which is a relevant range for bone tissue engineering [5, 18, 41–44]. We also observed a decline in uniformity with higher layers, which is common for 3D printed scaffolds.…”

“…For future in vivo implantation, 3D printed PPF-HA scaffolds can provide improved mechanical support for load-bearing implants as compared to PPF-HA scaffolds fabricated via indirect casting [49], molds [27], or STL [44, 50]. Furthermore, the osteoconductive properties of HA would allow bone to form within the scaffold’s pores and integrate with the surface.…”

Fabrication and in vitro evaluation of an articular cartilage extracellular matrix-hydroxyapatite bilayered scaffold with low permeability for interface tissue engineering

“…Lee et al . [32] evaluated the permeability of 3D porous poly (propylene fumarate) scaffolds with a controlled pore size architecture using the falling head method. Additionally, Al-Munajjed et al .…”

3D printing of resorbable poly(propylene fumarate) tissue engineering scaffolds

“…65 Three-dimensionalprinted polymers contain elaborate structures with internal hard-to-reach spaces that simple spray-coating would never reach. Dip-coating or soaking the material in solutions for further processing allows for penetration into internal porous spaces.…”