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Dissertation_Yufu Ren_ 2017.pdf (5.53 MB)

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Microwave Assisted Synthesis of Alkaline Earth Phosphate Coating and its Applications for Biomedical Implants

Ren, Yufu
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513204146096617

Abstract Details

2017, Doctor of Philosophy, University of Toledo, Mechanical Engineering.
Bioimplant is a group of medical devices that aim to restore/replace the function of the defected/diseased tissue. As the potential candidate for orthopedic applications, the implant material needs to maintain the suitable mechanical properties and desirable surface chemistry to ensure long-term mechanical stability and foster the regeneration of host tissue at the defect site. Due to the advancement in the research of biomaterials, a wide range of materials including metals, ceramics, polymers, and composites now can be used in bone grafting procedure for different purposes. However, none of the currently available bioimplant materials have met all the requirements and expectations. For instance, most of the metallic implant materials with high strength present poor osseointegration properties. Hence, there have been great efforts in developing the alkaline earth phosphate based bioactive coatings on implant materials to promote bone mineralization. This study covers diverse types of surface modifications of metallic implant material – magnesium alloy and polymeric implant material – polyetheretherketone (PEEK) with various alkaline earth phosphate coatings, nanostructuring, composite formation and surface pretreatments. In the first part of this thesis, a microwave assisted coating technique was developed to improve in vitro degradation behavior and biological properties of Mg alloys. The microwave irradiation dramatically accelerated coating deposition kinetics and notably shortened the coating process to minutes rather than hours/days consumed in the conventional biomimetic coating method. Moreover, the as-deposited calcium deficient hydroxyapatite (CDHA) and magnesium phosphate (MgP) layers presented outstanding corrosion resistance and bioactivity in physiological environment, which evidently enhanced the biological responses of Mg alloys. Further on, organic-inorganic composite coatings were synthesized by combining the microwave assisted coating technique with spin coating process and the synergistic benefits of as-deposited composite coatings were explored. It was found the alkaline earth phosphate nanoparticles including FHA and AMP, either serving as the interlayer between the polymer film and Mg alloy substrate or incorporating in polymer matrix, were beneficial to enhance biomineralization capability of Mg alloys and subsequently facilitate the osseointegration process. Moreover, organic layer-biodegradable PLA film presented excellent interlocking with alkaline earth phosphate phases, which leads to the formation of favorably compact microstructures of composite coatings. Consequently, as-deposited FHA/PLA and nAMP/PLA composite coatings were demonstrated to be efficacious in blocking the infiltration of the corrosive medium. In the end, an approach incorporating surface activation pretreatment and amorphous alkaline earth phosphate coating deposition was developed to overcome the inherent biological inertness of polyetheretherketone (PEEK). The pretreatment involves the acid or alkali etching could generate the negative charge on the surface of PEEK, which is fundamental to induce rapid deposition of amorphous magnesium phosphate (AMP) coating via the microwave assisted coating technique. The 3-D porous structure resulted by sulfonation in combination with bioactive AMP layer showed great ability to promote osteoblast attachment. More importantly, a more vigorous biomineralization process with greatly intensified bone-like apatite precipitation was observed on AMP coated PEEK samples in vitro, which reveals the tremendous potential of using amorphous alkaline earth phosphate coatings to improve the bioactivities of biomedical implants.
Sarit Bhaduri (Committee Chair)
Vijay Goel (Committee Member)
Arunan Nadarajah (Committee Member)
Ahalapitiya Jayatissa (Committee Member)
Matthew Franchetti (Committee Member)
206 p.
Materials Science; Mechanical Engineering
Microwave synthesis, Calcium phosphate, Magnesium phosphate

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Citations

  • Ren, Y. (2017). Microwave Assisted Synthesis of Alkaline Earth Phosphate Coating and its Applications for Biomedical Implants [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513204146096617

    APA Style (7th edition)

  • Ren, Yufu. Microwave Assisted Synthesis of Alkaline Earth Phosphate Coating and its Applications for Biomedical Implants. 2017. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513204146096617.

    MLA Style (8th edition)

  • Ren, Yufu. "Microwave Assisted Synthesis of Alkaline Earth Phosphate Coating and its Applications for Biomedical Implants." Doctoral dissertation, University of Toledo, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513204146096617

    Chicago Manual of Style (17th edition)

toledo1513204146096617
419
© 2017, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.