CALCIUM DOPED CITRATE BOUND BIOMATERIALS FOR MULTIFUNCTIONAL ORTHOPEDIC TISSUE ENGINEERING APPLICATIONS
Open Access
- Author:
- Fadel, John Elias
- Area of Honors:
- Biomedical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Jian Yang, Thesis Supervisor
Dr. William O Hancock, Thesis Honors Advisor
Dr. Justin Lee Brown, Faculty Reader - Keywords:
- Bone
orthopedics
orthopedic engineering
tissue engineering
bone implant
polymer
polymer engineering
characterization
materials - Abstract:
- Bone has become the second most transplanted tissue, only behind blood, with more than $30 billion spent annually in orthopedic related medical costs [1]. Previous research has confirmed the presence of strongly bound citrate-rich molecules that serve to stabilize the apatite nanocrystals within natural bone. The regulation of apatite nanostructure and the formation of apatitic calcium phosphate crystals impart natural bone with its mechanical properties and citrate is now thought to be a critical component in bone metabolism [2]. A citrate based, biodegradable elastomer, poly (1,8-octanediol-co-citric acid) (POC), has been developed, displaying excelled in vitro and in vivo biocompatibility; however, pure POC materials display insufficient mechanical properties in hydrated conditions, rapid degradation, and insufficient osteoconductivity [3]. Multiple ions, including calcium, are present throughout the body fluid and tissues, with roles in diverse biological processes including bone regeneration [4]. Citric acid, a polycarboxylic acid present in POC, readily chelates with cationic species and thus the addition of ionic species to POC results in the formation of a secondary, reversible ionic network, capable of improving mechanical strength while maintaining elasticity. Furthermore, the addition of calcium ions to POC is capable of imparting the bioactivity of the incorporated species into the resulting material. In this study, the development of a secondary ionic network was the focus as well as expanding the versatility of POC and its functional capabilities. Through various synthesis doping modifications, ionic doping sources, and a plethora of studies to characterize and test the formulated materials, this innovative design has solidified an enhanced polymer material for orthopedic applications. Calcium doping of POC has displayed improved mechanical strength in both dry and hydrated conditions with the maintenance of elastomeric character, shortened degradation rate, decreased swelling, minimal soluble content, improved cytocompatibility, a high degree of homogeneity, and a wide versatility in scaffold fabrication and molar concentration variability.