Single Layer Graphene Promotes Neuronal Activity by Regulating Potassium Ion Channels in Cultured Neuronal Networks

Abstract

Graphene, with its peculiar bi-dimensional crystal arrangement of pure carbon atoms, is catching the eye of the research community with its extraordinary physicochemical properties. In particular, single layer graphene (SLG) potential applications in biology and (nano)medicine have being deeply investigated during last years. Although preliminary reports have shown that graphene based materials can be safely interfaced with neuronal cells (Fabbro et al., 2015), to date an exhaustive functional study of neuronal networks developed interfaced with SLG is missing. Here, for the first time, we show that uncoated SLG is not only fully biocompatible but, surprisingly, induces in cultured neurons an increased network synaptic activity, presumably by altering the availability of extracellular K+ ions. The homeostatic changes observed in SLG-interfaced cells, as well as the increased network activity, were not observed when neurons were grown neither on a many-layers graphene (MLG), nor onto thin gold substrates, suggesting a highly material specificity of this adaptive interaction. In particular, combining material characterization, electrophysiological patch-clamp recordings and neuronal network simulations, we propose a model in which the peculiar interaction of SLG with the ionic species present in solution shifts a significant fraction of phasically firing neurons towards a tonic phenotype, and these changes are reflected as an increased firing activity at the entire network level.