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Gellan Gum Based Thiol-Ene Hydrogels with Tunable Properties for Use As Tissue Engineering Scaffolds Zihao Xu Iowa State University

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Gellan Gum Based Thiol-Ene Hydrogels with Tunable Properties for Use As Tissue Engineering Scaffolds Zihao Xu Iowa State University Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2018 Gellan gum based thiol-ene hydrogels with tunable properties for use as tissue engineering scaffolds Zihao Xu Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Materials Science and Engineering Commons, and the Mechanics of Materials Commons Recommended Citation Xu, Zihao, "Gellan gum based thiol-ene hydrogels with tunable properties for use as tissue engineering scaffolds" (2018). Graduate Theses and Dissertations. 16493. https://lib.dr.iastate.edu/etd/16493 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Gellan gum based thiol-ene hydrogels with tunable properties for use as tissue engineering scaffolds by Zihao Xu A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Materials Science and Engineering Program of Study Committee: Kaitlin Bratlie, Co-major Professor Shan Jiang, Co-major Professor Surya Mallapragada The student author, whose presentation of the scholarship herein was approved by the program of study committee, is solely responsible for the content of this thesis. The Graduate College will ensure this thesis is globally accessible and will not permit alterations after a degree is conferred. Iowa State University Ames, Iowa 2018 Copyright © Zihao Xu, 2018. All rights reserved. ii TABLE OF CONTENTS Page LIST OF FIGURES ........................................................................................................... iv LIST OF TABLES .............................................................................................................. v NOMENCLATURE .......................................................................................................... vi ACKNOWLEDGMENTS ................................................................................................ vii ABSTRACT ..................................................................................................................... viii CHAPTER 1. CLICK CHEMISTRY HYDROGELS IN TISSUE ENGINEERING APPLICATIONS ................................................................................................................ 1 1. Introduction ......................................................................................................... 1 2. Hydrogel crosslinking mechanisms .................................................................... 2 2.1. Click chemistry crosslinking ......................................................................... 3 2.1.1. Diels-Alder reaction .............................................................................. 5 2.1.2. Azide and alkyne cycloaddition ............................................................ 7 2.1.3. Chain growth mechanism .................................................................... 10 2.1.4. Thiol-ene chemistry ............................................................................. 12 3. Click chemistry hydrogels ................................................................................ 18 3.1. Synthetic polymer based hydrogels ............................................................. 18 3.1.1. PEG ...................................................................................................... 19 3.1.2. PVA ..................................................................................................... 22 3.2. Natural polymer based hydrogels ................................................................ 23 3.2.1. Chitosan ............................................................................................... 23 3.2.2. Gelatin ................................................................................................. 25 3.2.3. Hyaluronic acid hydrogels ................................................................... 27 4. Hydrogels fabricated using click chemistry as tissue scaffolds ........................ 28 5. Conclusions and future perspectives ................................................................. 30 CHAPTER 2. GELLAN GUM BASED THIOL-ENE HYDROGELS WITH TUNABLE PROPERTIES FOR USE AS TISSUE ENGINEERING SCAFFOLDS...... 32 1. Introduction ....................................................................................................... 32 2. Methods and materials ...................................................................................... 34 2.1. Materials ...................................................................................................... 34 2.2. Gellan gum modification ............................................................................. 34 2.3. Characterization of modification of gellan gum .......................................... 34 2.4. Synthesis of hydrogels ................................................................................. 35 2.5. Compressive modulus .................................................................................. 36 2.6. Swelling ratio ............................................................................................... 36 2.7. In vitro degradation profile .......................................................................... 36 2.8. Cell Culture .................................................................................................. 37 2.9. Cell Proliferation.......................................................................................... 37 iii 2.10. Statistics and data analysis .................................................................. 38 3. Results and discussion ...................................................................................... 38 3.1. Gellan gum modification and characterization ............................................ 38 3.2. Compression modulus.................................................................................. 39 3.3. Swelling ratio ............................................................................................... 43 3.4. In vitro degradation ...................................................................................... 46 3.5. Cell Proliferation.......................................................................................... 48 4. Conclusion ........................................................................................................ 51 CHAPTER 3. EFFECT OF SUBSTRATE HYDROPHOBICITY ON CELL PROLIFERATION AND POLARIZATION ON GELLAN GUM BASED HYDROGEL..................................................................................................................... 53 1. Introduction ....................................................................................................... 53 2. Methods and materials ...................................................................................... 55 2.1. Materials ...................................................................................................... 55 2.2. Hydrophobic modification ........................................................................... 55 2.3. Characterization of the modified gellan gum .............................................. 56 2.4. Hydrogel fabrication .................................................................................... 56 2.5. Compression modulus.................................................................................. 57 2.6. Swelling ....................................................................................................... 57 2.7. Water contact angle ..................................................................................... 57 2.8. Cell culture ................................................................................................... 58 2.9. Cell proliferation .......................................................................................... 58 2.10. Griess assay ......................................................................................... 59 2.11. Urea assay ............................................................................................ 59 2.12. Statistics and data analysis .................................................................. 59 3. Results and discussion ...................................................................................... 60 3.1. LMGG hydrophobic modification and characterization .............................. 60 3.2. Compression modulus.................................................................................. 61 3.3. Swelling of hydrogels .................................................................................. 63 3.4. Water contact angle ..................................................................................... 64 3.5. Cell proliferation .......................................................................................... 66 3.6. Cell polarization ........................................................................................... 68 4. Conclusion ........................................................................................................ 72 REFERENCES ................................................................................................................. 73 iv LIST
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