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A Thesis Entitled Development of Novel Magnesium Phosphate Bone A Thesis entitled Development of Novel Magnesium Phosphate Bone Cement by Niloufar Rostami Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Bioengineering ________________________________________ Dr. Sarit B. Bhaduri, Committee Chair ________________________________________ Dr. Vijay K. Goel, Committee Member ________________________________________ Dr. Arunan Nadarajah, Committee Member ________________________________________ Dr. Mehdi Pourazady, Committee Member ________________________________________ Dr. Patricia R. Komuniecki, Dean College of Graduate Studies The University of Toledo December 2014 Copyright 2014, Niloufar Rostami This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author. An Abstract of Development of Novel Magnesium Phosphate Bone Cement by Niloufar Rostami Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Master of Science Degree in Bioengineering The University of Toledo December 2014 This study aims to develop a novel magnesium phosphate based injectable cement for orthopedic applications. Magnesium phosphate cements (MPC) provide more favorable clinical performances including shorter setting time, and higher resorption rates and strength, as compared to the commonly used calcium phosphate cements. These features make magnesium cements great potential candidates for orthopedic and dental applications. In this study, the magnesium phosphate cement is prepared using a microwave assisted precipitation process. An experimental study is conducted to evaluate developed phases, setting times, injectability, and mechanical strength of the prepared cement. X-ray diffraction and SEM techniques are used to characterize the structure of powders with or without physiological conditions. Physiological conditions are simulated by soaking MPC pellets in Simulated Body Fluid (SBF). To determine the cytotoxicity effects of the as-synthesized magnesium phosphate cements, the mammalian preosteoblast cells are cultured on the MPC samples and the biocompatibility of the materials is confirmed. iii Dedicated to my Family Acknowledgements I would like to thank my advisor Dr Sarit B. Bhaduri for his support, caring, patience, and providing me with an excellent atmosphere through my master’s thesis research. Moreover, I would also like to thank Dr. Huan Zhou who patiently guided me through the research process. In addition thank to Dr Anand Agarwal for his support and his assistance. I would like to thank Tammy Phares and Dr. Joseph Lawrence in the bioengineering department and in the center for materials and sensor characterization, respectively, for their assistance. Lastly, I would also like to thank Dr. Vijay K. Goel, Dr. Mehdi Pourazady, and Dr. Arunan Nadarajah who were willing to participate in my defense committees. I am sincerely grateful to my lab mates Maryam Nabiyouni, Elham Babaie, and Sameh Saleh for sharing their truthful and illuminating views on a number of issues related to the thesis. I would like to thank my husband, Vahid Mortazavian for his aspiring guidance through my master’s thesis. I am thankful for his patience, support and love. Most importantly, I would like to thank my family for their love and patience. None of this would have been possible without their support. v Table of Contents Abstract .............................................................................................................................. iii Acknowledgements ..............................................................................................................v Table of Contents ............................................................................................................... vi List of Tables ................................................................................................................. viii List of Figures .................................................................................................................... ix List of Abbreviations ......................................................................................................... xi List of Symbols ................................................................................................................. xii 1 Introduction.................. ............................................................................................1 2 Literature Review.....................................................................................................4 2.1 Introduction ........................................................................................................4 2.2 Biological and Orthopedic Background .............................................................7 2.3 Magnesium Phosphate Cement ..........................................................................9 2.3.1 Magnesium Phosphate System Studies .............................................10 2.3.2 Rheological and Biological Studies ..................................................14 2.3.3 Essential Factors for Magnesium Phosphate Cement .......................18 3 Materials and Methods ...........................................................................................20 3.1 Preparation of MgP Powder .............................................................................20 3.2 Fabrication of Cement Samples .......................................................................21 3.3 Working Time and Setting Time Measurement...............................................21 vi 3.4 Injectability ......................................................................................................22 3.5 Compression Strength ......................................................................................23 3.6 In vitro Evaluation ...........................................................................................23 3.7 Acellular Bioactivity by Soaking in SBF.........................................................25 3.8 Characterization of Powders ............................................................................26 3.8.1 X-Ray Diffraction Analysis ..............................................................26 3.8.2 Phase Composition and Morphology of Cement ..............................26 3.9 Statistical Analysis ...........................................................................................27 4 Results…….….…….….. .......................................................................................28 4.1 Phase Composition of Cements Powder ..........................................................27 4.2 Cement Morphology ........................................................................................30 4.3 Setting Time .....................................................................................................38 4.4 Injectability ......................................................................................................40 4.5 Compressive Strength ......................................................................................41 4.6 Strength While Setting .....................................................................................43 4.7 In vitro Evaluation ...........................................................................................44 4.8 Summary and discussion..................................................................................46 References ..........................................................................................................................50 vii List of Tables 2.1 Critical requirements for bone cement .....................................................................5 2.2 Hydrated magnesium phosphate (low temperature) ..............................................11 3.3 Composition of 1 L test SBF .................................................................................26 4.4 Setting times of MPC for boric acid and borax with L/P ratio of 0.33 ..................40 4.5 Mechanical strength of MPC for boric acid and borax ..........................................41 4.6 Strength while setting for MPC samples ...............................................................43 4.7 Unadjusted plate reader results day 1 ....................................................................44 4.8 Unadjusted plate reader results day 7 ....................................................................44 viii List of Figures 2-1 Magnesium-related studies over 20 years (data from literature) .............................7 2-2 Total distribution of magnesium in the human body ...............................................8 2-3 Ternary system MgO-P2O5-H2O at 25 °C ............................................................10 2-4 Struvite crystals development ................................................................................13 3-5 MPC samples soaked in SBF for 7 days ................................................................25 4-6 XRD scan of MPC powder after 24 hours .............................................................29 4-7 Scanning electron characterization of MPC, 10000X Magnification ....................30 4-8 SEM characterization of MPC after 7 days of SBF incubation, 1000X magnification (a, b), 400X magnification (c)................................................................................31 4-9 SEM-EDS analysis revealed that MPC surface soaked in SBF is
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