Supercritical carbon dioxide-processed resorbable polymer nanocomposites for bone graft substitute applications

<p>Numerous clinical situations necessitate the use of bone graft materials to enhance bone formation. While autologous and allogenic materials are considered the gold standards in the setting of fracture healing and spine fusion, their disadvantages, which include donor site morbidity and finite supply have stimulated research and development of novel bone graft substitute materials. Among the most promising candidate materials are resorbable polymers, composed of lactic and/or glycolic acid. While the characteristics of these materials, such as predictable degradation kinetics and biocompatibility, make them an excellent choice for bone graft substitute applications, they lack mechanical strength when synthesized with the requisite porous morphology. As such, porous resorbable polymers are often reinforced with filler materials. In the presented work, we describe the use of supercritical carbon dioxide (scCO₂) processing to create porous resorbable polymeric constructs reinforced by nanostructured, organically modified Montmorillonite clay (nanoclay). scCO₂ processing simultaneously disperses the nanoclay throughout the polymeric matrix, while imparting a porous morphology to the construct conducive to facilitating cellular infiltration and neoangiogenesis, which are necessary components of bone growth. With the addition of as little as 2.5wt% of nanoclay, the compressive strength of the constructs nearly doubles putting them on par with human cortico-cancellous bone. Rheological measurements indicate that the dominant mode of reinforcement of the nanocomposite constructs is the restriction of polymer chain mobility. This restriction is a function of the positive interaction between polymer chains and the nanoclay. In vivo inflammation studies indicate biocompatibility of the constructs. Ectopic osteogenesis assays have determined that the scCO₂-processed nanocomposites are capable of supporting growth-factor induced bone formation. scCO₂-processed resorbable polymer nanocomposites composed of resorbable polymers and nanocaly exhibit physical, mechanical and biologic properties that make them excellent candidate materials for structural bone graft substitute applications.</p>

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Open Access Dissertation

Discipline thesis:degree_discipline

Biomedical Engineering

Year dc:date.available

2011

Author dc:creator

• Baker, Kevin

Contributors dc:contributor

• Rangaramanujam M. Kannan

• Bone graft
• Bone tissue engineering
• Nanoclay
• Nanocomposite
• Supercritical carbon dioxide
• Biomedical Engineering and Bioengineering
• Materials Science and Engineering

Repository record dc:identifier

https://digitalcommons.wayne.edu/oa_dissertations/268

OAI identifier oai:identifier

oai:digitalcommons.wayne.edu:oa_dissertations-1267