Session: Research Posters

Paper Number: 110406

110406 - Investigation of the Mechanical Properties of Triply Periodic Minimal Surface Bone Scaffolds, Composed of Poly(lactic-Co-Glycolic Acid), Nanoclay, and Hydroxyapatite 

Treatment of bone fracturs in clinical practice is a complex medical process, where factors, such as material viscosity, stiffness, biodegradability, play a significant role in the dynamics of angiogenesis, osteogenesis, and ultimately fracture healing. The overarching goal of this research work is to synthesize and subsequently fabricate mechanically robust, biocompatible, and porous bone scaffolds for treatment of bone pathology. In pursuit of this goal, the overall objective of the work is to investigate the influence of polylactic-co-glycolic acid (PLGA), nanoclay (NC), and hydroxyapatite (HA) concentrations on the mechanical properties of bone scaffolds, fabricated using pneumatic micro-extrusion (PME) process. PME is a high-resolution additive manufacturing method, which has been utilized for fabrication of a board spectrum of biological tissues and constructs. This work tests the following central hypothesis (H₀): biocompatible, composite bone tissue scaffolds with complex micro-structures (composed of PLGA along with NC and HA) are fabricated using PME process. The specific aim of the work is to identify optimal concentrations of PLGA, NC, and HA as well as material deposition regimes, which will lead to high compression strength. In this study, based on designed experiments, the PLGA concentration as well as NC/HA concentration were changed in the range of 80-99 wt. % and 1-5 wt. %, respectively. To prepare a uniform composite for 3D-fabriction, PLGA (togther with NC, HA, and NC+HA) was dissolved and continuously mixed in 25 mL of acetone (used as the solvent) for 75 minutes and subsequently oven-dried at 60 °C (which is within the glass transition temperature of PLGA) for 24 hours to allow for complete evaporation of the solvent. The resulting PLGA-NC, PLGA-HA, and PLGA-NC-HA composites were, then, collected as small pieces and loaded into the cartridge of the material deposition system. Porous bone scaffolds (based on triply periodic minimal surfaces, including Schwarz Gyroid, Schwarz Primitive, and Schwarz Diamond microstructures) were PME-fabricated using a thermoplastic deposition head (heated at 150 °C) having a nozzle diameter of 400 μm. Furthermore, print speed as well as pneumatic flow pressure were set at 2.5 mm/s and 100 kPa, respectively. The material deposition was highly viscous and laminar on a glass substrate heated at 50 °C (which allowed for safe scaffold detachment from the surface despite the brittle nature of PLGA after deposition). Overall, the outcomes of this study pave the way for fabrication of mechanically robust and porous bone tissue scaffolds with complex internal micro-structures as well as advanced osteogenic properties.

Presenting Author: Ethan O'malley Marshall University

Presenting Author Biography: Mr. Ethan O'malley is a graduate student of mechanical engineering working under the direction of Dr. Ross Salary at Marshall University.

Authors:

Ethan O'malley Marshall University
Roozbeh (Ross) Salary Marshall University