DEVELOPMENT OF A NOVEL MAGNESIUM DOPED CITRATE BASED POLYMER COMPOSITE FOR ORTHOPEDIC ENGINEERING
Open Access
- Author:
- Rahn, Kevin Michael
- Area of Honors:
- Biomedical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Jian Yang, Thesis Supervisor
Jian Yang, Thesis Honors Advisor
Dr. Justin Lee Brown, Faculty Reader - Keywords:
- bone
bone engineering
orthopedic engineering
citrate-based materials
magnesium oxide
polymer
tissue engineering
injection molding - Abstract:
- Current bone substitute materials vary greatly both in their manufacturing techniques and compositions, but many still lack the mechanical, biological, and fabrication properties for a clinically ready bone substitute material. The goal of this study was to develop a novel self-setting polymer/ceramic composite bone cement with improved manufacturability through the use of a citrate polymer, a calcium phosphate mineral phase, and magnesium oxide as a self-setting agent. Magnesium oxide (MgO) was shown to quickly self-set POC (poly (octamethylene citrate)) polymer and POC/hydroxyapatite (HA) composites suitable as bone tissue substitute materials. A predictive model for the setting time of the cement as a function of cement composition was developed, as well as a preliminary setting reaction mechanism model for the cement. The mechanical properties of the cement, including the peak stress, Young’s modulus, and peak strain were characterized and shown in cases of lower MgO concentrations to significantly improve the peak stress and Young’s modulus of the material. Additionally, the cytotoxicity, degradation, pH response, and swelling response of the material were shown to be either comparable, or an improvement on POC/HA control composites. Finally, and most notably, the increased ease of fabrication of porous and solid scaffolds through injection molding was demonstrated, providing a drastic improvement on current routes of fabrication for POC/HA composites. The applicability of magnesium oxide self-setting was also demonstrated in other polymers of the citrate polymer family, including crosslinked urethane doped polyester elastomers (CUPE), biodegradable photoluminescent polymer (BPLP), and POC-click.