The Structural Biodegradation of Graphene Oxide In Vivo A thesis submitted to the University of Manchester for the degree of Doctor of Philosophy in the Faculty of Biology, Medicine & Health Leon Newman School of Health Sciences, Division of Pharmacy and Optometry 2017 Table of Contents List of Figures ..................................................................................................................... 5 List of Tables ..................................................................................................................... 10 Abstract ............................................................................................................................. 12 Declaration ........................................................................................................................ 13 Declaration ..................................................................................................................... 13 Copyright statement ...................................................................................................... 13 Acknowledgements .......................................................................................................... 14 Rationale for the alternative thesis format ...................................................................... 15 List of abbreviations ......................................................................................................... 16 Chapter 1 ........................................................................................................................... 18 1. Introduction. ............................................................................................................... 18 1.1. Introduction and overview of thesis contents. ................................................. 18 1.2. References .......................................................................................................... 23 Chapter 2 ........................................................................................................................... 24 2. Understanding the degradability of sp2 hybridised carbon nanomaterials for their applications in biomedicine ............................................................................................. 24 2.1. Statement. ........................................................................................................... 24 2.2. Abstract. .............................................................................................................. 25 2.3. Introduction. ........................................................................................................ 26 2.3.1. sp2 hybridised CNMs. .................................................................................. 27 2.3.2. Fullerenes. .................................................................................................... 27 2.3.3. Carbon nanotubes. ...................................................................................... 28 2.3.4. Carbon nanohorns. ...................................................................................... 30 2.3.5. Graphene. ..................................................................................................... 32 2.3.6. Functionalised derivatives. ......................................................................... 33 2.4. Degradation and the use of CNMs in biomedicine. .......................................... 35 2.5. Chemically mediated degradation. .................................................................... 36 2 2.5.1. Overview of chemical mediated CNM degradation and the lessons learnt. ...................................................................................................................... 42 2.6. Enzyme catalysed biodegradation. ................................................................... 46 2.6.1. The peroxidase enzyme superfamily. ......................................................... 46 2.6.2. Horse radish peroxidase. ............................................................................ 46 2.6.3. Myeloperoxidase. ......................................................................................... 51 2.6.4. Other enzymes. ............................................................................................ 54 2.6.5. Overview of enzyme mediated CNM biodegradation and the lessons learnt. ...................................................................................................................... 57 2.7. Biodegradation mediated by cells. .................................................................... 61 2.7.1. Neutrophils. .................................................................................................. 61 2.7.2. Macrophages................................................................................................ 65 2.7.3. Microglia. ...................................................................................................... 67 2.7.4. Overview of cell mediated CNM biodegradation and the lessons learnt. 71 2.8. Biodegradation of CNMs in vivo. ....................................................................... 76 2.8.1. Biodegradation of CNMs in the lungs. ....................................................... 76 2.8.2. Biodegradation of CNMs in other tissues. ................................................. 79 2.8.3. Overview of in vivo mediated CNM biodegradation and the lessons learnt. ...................................................................................................................... 80 2.8.4. Summary of the factors that can be used to modulate CNMs biodegradation relevant to biomedicine................................................................... 84 2.9. Products of degradation and their health effects. ............................................ 84 2.10. Biodegradation requirements for CNM based biomedical applications and beyond. .......................................................................................................................... 87 2.10.1. Drug delivery. ............................................................................................... 87 2.10.2. Tissue engineering. ..................................................................................... 91 2.10.3. Diagnostics and monitoring. ....................................................................... 94 2.10.4. Summary of the need to consider CNM biodegradation in relation to their biomedical applications. ........................................................................................... 96 2.11. Conclusion. ...................................................................................................... 97 3 2.12. References. ...................................................................................................... 99 Chapter 3 ......................................................................................................................... 115 3. Hypothesis, Aims and Objectives .............................................................................. 115 Chapter 4 ......................................................................................................................... 117 4. Hypochlorite Degrades 2D Graphene Oxide Sheets Faster than 1D Oxidised Carbon Nanotubes and Nanohorns ............................................................................... 117 4.1. Statement. ............................................................................................................. 117 4.2. Abstract. ................................................................................................................ 118 4.3. Introduction. ......................................................................................................... 119 4.4. Results. ................................................................................................................. 121 4.5. Discussion. ........................................................................................................... 127 4.6. Experimental. ........................................................................................................ 135 4.7. Acknowledgements. ............................................................................................. 138 4.8. Supplementary information ................................................................................. 139 4.9. References ............................................................................................................ 148 Chapter 5 ......................................................................................................................... 152 5. Splenic capture and in vivo intracellular biodegradation of thin, biological-grade graphene oxide sheets ................................................................................................... 152 5.1. Statement. ............................................................................................................. 152 5.2. Abstract. ................................................................................................................ 153 5.3. Introduction. ......................................................................................................... 154 5.4. Results. ................................................................................................................. 156 5.5. Discussion. ..........................................................................................................