Thesis
The effects of SiO₂, ZnO, and MgO doping on the mechanical and biological properties of beta-tricalcium phosphate bioceramics for bone tissue engineering, in vitro and in vivo analysis
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/101340
Abstract
Beta-tricalcium phosphate ([Beta]TCP) is a promising bioresorbable ceramic for bone grafting applications that displays excellent biocompatibility because of its chemical similarity to natural bone. However, [Beta]TCP displays a relatively fast and uncontrolled dissolution rate, which leads to strength reduction over time - limiting its applications. One method of controlling the fast degradation rate, and subsequent strength loss, is through the introduction of metal oxide dopants. The objective of this research is to evaluate the influence of SiO2, ZnO, and MgO on the strength loss characteristics and biocompatibility of [Beta]TCP through in vitro and in vivo studies. Three doped compositions of [Beta]TCP were selected for in vitro analysis based on preliminary testing and literature review: i) [Beta]TCP + 0.5wt% SiO2, ii) [Beta]TCP + 0.5wt% SiO2+ 0.25wt% ZnO, iii) [Beta]TCP + 0.5wt% SiO2+ 0.25wt% ZnO + 1.0wt% MgO. From this study, a single composition, (ii), was selected for inclusion in a preliminary in vivo study. Dense ceramic samples were manufactured from phase pure [Beta]TCP nanocrystals, then characterized based on density, grain size, phase purity, and mechanical strength. In vitro testing subjected samples to 16 weeks in a simulated body fluid solution in order to test mechanical strength loss, weight change, dissolution, and bioactivity. In vivo samples were implanted for 16 weeks into the distal femur or lateral condyle of male Sprague-Dawley rats to assess tissue integration, implant degradation, and bone regeneration within the physiological environment. In vitro, all three dopant compositions affected the densification, grain size, and initial mechanical strength of [Beta]TCP. Additionally, compositions (ii) and (iii) exhibited decreased strength loss over time compared to [Beta]TCP - indicating that these compositions are promising candidates for select bone grafting applications. Consistent with published research, the in vivo implants displayed excellent biocompatibility as demonstrated by post-operative recovery of the animals. Both control and doped compositions showed signs of degradation, mechanical integration, and tissue in-growth at the implant-tissue interface. Compared to the control animals, the animals which received implants showed the highest blood serum concentrations of osteocalcin, sulfated glycosaminoglycans, and collagen.
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Details
- Title
- The effects of SiO₂, ZnO, and MgO doping on the mechanical and biological properties of beta-tricalcium phosphate bioceramics for bone tissue engineering, in vitro and in vivo analysis
- Creators
- Scott Everett Rewinkel
- Contributors
- Susmita Bose (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525053501842
- Language
- English
- Resource Type
- Thesis