Dissertation
THE EFFECT OF SUBSTITUTED CHLORINE IN HYDROXYAPATITE (CLHAP) ON PHYSICAL, MECHANICAL AND BIOLOGICAL PROPERTIES – BULK AND COATED CLHAP
Doctor of Philosophy (PhD), Washington State University
01/2018
Handle:
https://hdl.handle.net/2376/116534
Abstract
Synthetic hydroxyapatite (HAp) bioceramics commonly serve as a non-load bearing implant due to their similar composition and porous structure with human bone. However, synthetic HAp bioceramics have insufficient mechanical properties and low bioactivity. The first objective is to understand the effect of substituted chlorine on mechanical and biological properties of sintered ClHAP biocermics.
The ClHAP bioceramics have high relative density (90.27 ~ 91.06%), Vickers hardness ~ 390 HV and compressive strength > 250 MPa. They are mainly composed of chlorine-bearing apatite and β-TCP phases. A higher ratio of substituted chlorine in ClHAP increases surface wettability, releases more acidity and chloride. The 2 - 10% ClHAP bioceramics maintain a same level of osteoblastic adhesion and proliferation as that on pure HA, which demonstrates their biocompatibility. A molar ratio of 2 - 10% substituted chlorine is optimal for in vivo performance because of their superior mechanical properties, enhanced bioactivity, osteoclastic activity, osteoblastic proliferation in vivo, and potential long-term osseointegration.
Titanium alloy (Ti-6Al-4V) is a commonly used load-bearing implant metal due to its biocompatibility, fatigue and corrosion resistance. However, Ti64 is bio-inert. The second objective is to promote bioactivity, wettability and osteoblastic compatibility on Ti64 surface via hydrothermal treatment in urea solutions. The hydrothermally treated Ti64 surface in 3 M urea has better hydrophilicity and higher Vickers hardness than the polished Ti64 surface as well as the formation of anatase TiO2 with the reduced surface roughness. The in-situ coating has a good adhesiveness to the Ti64 substrate.
The hydrothermally treated Ti64 surfaces do not apparently promote bioactivity. The bioactivity and biocompatibility of hydrothermally treated-Ti64 will be further promoted through the deposition of ClHAP/polydopamine composite coating. The finer ClHAP particles were anchored well and dispersed uniformly in the polydopamine coatings on Ti64 surface. The polydopamine leads to a gradual release of acidity and retards the release of chloride from ClHAP powder in vitro. The composite coatings display superhydrophilicity and combine the advantages of bioactive ClHAP powders and biocompatibile polydopamine. Therefore, the composite coatings are expected to promote both osteoclastic and osteoblastic activities. The osteoblastic activities are being tested by Dr. Bernards’ group.
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Details
- Title
- THE EFFECT OF SUBSTITUTED CHLORINE IN HYDROXYAPATITE (CLHAP) ON PHYSICAL, MECHANICAL AND BIOLOGICAL PROPERTIES – BULK AND COATED CLHAP
- Creators
- Chin-Shih Hsu
- Contributors
- Qizhen Li (Advisor)David P. Field (Committee Member)Yuehe Lin (Committee Member)Amit Bandyopadhyay (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Materials Science and Engineering Program
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 134
- Identifiers
- 99900581506201842
- Language
- English
- Resource Type
- Dissertation