2D materials in electrochemical sensors for in vitro or in vivo use.

Individual cells and cell populations are at the present time investigated with a myriad of analytical tools. While most of them are commercially available, some of these analytical tools are just emerging from research laboratories and are in the developmental phase. Electrochemical sensors which allow the monitoring of low molecular weight compounds released (and / or uptaken) by cells are among these emerging tools. Such sensors are increasingly built using 2D materials (e.g. graphene-based materials, transition metal dichalcogenides, etc.) with the aim of conferring better analytical performances to these devices. The present work critically reviews studies published during the last 10 years describing electrochemical sensors made with 2D materials and exploited to monitor small compounds (e.g. HO, ·NO, glucose, etc.) in living biological systems. It also discusses the very few 2D material-based electrochemical sensors which are wearable or usable in vivo. Finally, the present work includes a specific section about 2D material biocompatibility, a fundamental requirement for 2D material-based sensor applications in vitro and in vivo. As such, the review provides a critical view on the state of the art of electrochemical sensors made with 2D materials and used at cellular level and it evaluates the possibility that such sensors will be used on / in the human body on a wider scale.