On the interpretation of astrocytic calcium signalling with graphene oxide electrodes.

In a recent paper, Fabbri et al.1 claimed that the contrasting electrical properties of graphene oxide (GO), an insulating material, and reduced graphene oxide (rGO), a conductive material, could be exploited to selectively electrically stimulate either external Ca2+ influx or internal Ca2+ release in astrocytes, respectively. Furthermore, based on distinct temporal profiles of Ca2+ traces after stimulation via GO- versus rGO-coated ITO electrodes—with onsets delayed by up to 3 min—they suggested that astrocytes have the ability to sense distinct electric fields caused by the presence of insulating or conductive interfaces. Here we comment on some fundamental contradictions and experimental inconsistencies in the study.