Diamond - towards a "one material" multi electrode array for neuronal recording

Abstract

Event Abstract Back to Event Diamond - towards a "one material" multi electrode array for neuronal recording Paul A. Nistor1, 2, Paul W. May2 and Maeve A. Caldwell1 1 University of Bristol, Regenerative Medicine Laboratory, United Kingdom 2 University of Bristol, School of Chemistry, United Kingdom Introduction: Neuronal network activity can be investigated by in vitro neuronal recording, using Multi Electrode Arrays (MEAs). The advent of MEAs opened the possibility of simultaneous recording from multiple interconnecting neurons. The efficiency of the method is however dependent on the duration for which the cells can be maintained viable and functional; usually this ranges from hours to a few days. One critical aspect concerns the incompatibility between metallic electrodes and the cells which generate an electrical signal. To address this, frequently, the electrodes are coated in “bio-friendly” materials. Thus, a separation is introduced between the cellular and electrical interface, with consequences on the resolution of signal, particularly important for low, synaptic, currents. Diamond is a material investigated as a possible interface material for neurons: it is biologically inert, it does not induce an immune response when implanted[1],[2] and it has been shown to be supportive for neuronal growth and differentiation[3],[4]. Furthermore, diamond, which is insulating when pure, can be made semiconductive by doping with electron acceptors or donors, one example being boron. We propose here a MEA which is fully biocompatible and for which the insulating and conductive parts are made from the same material: diamond. Material and Methods: Diamond films can be produced relatively inexpensively by the method of chemical vapour deposition. In this work, a thin (5 µm) film of conductive boron-doped diamond was deposited onto a synthetic pure diamond substrate. Conductive diamond electrodes were then revealed by selective laser etching of the boron-doped diamond layer. Human pluripotent stem cells were then differentiated onto diamond substrates, using a specifically developed protocol[5]. After 2-4 months, when these cells had formed mature neurons, the interaction with the diamond substrate was assessed. Results and Discussion: Neurons differentiated in vitro, from human pluripotent cells, can be maintained on our diamond substrates for many weeks without the loss of viability or function. No difference was observed in the supportive properties of boron-doped diamond versus diamond. Scanning Electron Microscopy revealed that the neurons interacted intimately with the substrate, both at the cell body and neurite level. This study represents a step towards the production of a fully biocompatible single material MEA for the in vitro study of neuronal network activity. Furthermore, we provide a platform for the investigation of artificial human neuronal networks, with the aim of challenging the “animal model” supremacy, which has dominated the neuronal electrophysiology studies for decades. Conclusion: We present here a novel diamond MEA for optimal neuronal electrical recording. We significantly increased the time cells can be maintained in culture, a fundamental prerequisite for the study of long-term neuronal plasticity. Furthermore, the neurons used are derived form human pluripotent cells, which can be sourced from patients and thus, amenable to targeted drug screening studies. Dr. James Smith (School of Chemistry) for outstanding technical support; Dr. Tilo Kunath (University of Edinburgh) for the kind gift of NAS2 hIPS cell line and advice; This research was supported by EPSRC grant numberP: EP/K002503/1