Single Layer Graphene Biointerface: Studying Neuronal Network Development and Monitoring Cell Behavior over Time

The objective of my Ph.D. thesis is the investigation of the role of Single Layer Graphene (SLG) as a biointerface for its possible future exploitation in various biomedical applications; in particular for the development of biosensors, substrates for regenerative medicine, interfacing platforms for better recording of electrophysiological activity of neuronal networks, among others. This Ph.D. project is multidisciplinary involving both the material transfer and characterization part from one side and the biological part from another side. The material part offers an in-depth explanation of SLG synthesis, transfer, characterization and functionalization while the biological section sheds light on the studies performed for investigation of the behavior of different types of cell lines on SLG substrates. For better understanding of the sequence of the performed work, I have divided this thesis into separate chapters. In the beginning and end of every chapter, I added an introduction and conclusions related to it. Chapter 1 acts as a general introduction to graphene and graphene-related materials where a detailed explanation on the evolution of those materials as a cell interface is provided leading to the introduction of SLG in the end of this chapter along with its production process. Chapter 2 is oriented on the surface characterization of SLG substrates; in this chapter, I described the SLG transfer method, creation of the micrometric ablated geometric patterns on the transferred substrates using excimer laser micromachining, a technique developed in our lab, then further functionalization of the substrates and finally all the techniques employed for their physicochemical characterization. Chapter 3 is dedicated to the biological part of the project; i.e. studying the behavior of different cell lines on the SLG substrates. In this chapter, I have described and explained the interest of using the selected cell lines and the experiments that were performed on them. Chapter 4 has been devoted to a complete and separate project that I performed in collaboration with the Neuroscience and Brain Technologies department. The main focus of the project was the functionalization of the commercial multi-electrode arrays (MEAs) with SLG and studying the neuronal network activity on them throughout the complete network development. Although the main focus of my Ph.D. project was studying SLG biointerface, I have also been involved in side projects, among which, studying the neuronal-like response of mouse neuroblastoma (N2a) living cells to nanoporous patterns of thin supported anodic alumina which I have described in Appendix A, and studying the surface potential of graphene by polyelectrolyte coating which I have presented in Appendix B. To summarize, this thesis reports an original investigation, since, to the best of our knowledge, there is no report yet about the study of the effect of SLG functionalized MEA on the neuronal network activity throughout the complete network maturation. Furthermore, proliferation curves of different cell lines on SLG versus control substrates have been presented; in addition to physicochemical characterization of ablated and functionalized SLG substrates as means of possible explanation of a certain cellular behavior on graphene.