Graphene Interfaced with Biological Cells: Opportunities and Challenges.

By interfacing the quantum mechanical properties of nanomaterials with the complex processes in biology, several bio/nano systems have evolved with applications in biosensors, cellular devices, drug delivery, and biophotoluminescence. One recent breakthrough has been the application of graphene, a two-dimensional (2-D) sheet of sp(2) hybridized carbon atoms arranged in a honeycomb lattice, as a sensitive platform for interfacing with biological cells to detect intra- and extracellular phenomena, including cellular excretion and cell membrane's potential modulation. In this Perspective, we discuss the recent results on graphene/cell interfacial devices and the principles defining the modulation of charge-carrier properties in graphene and its derivatives via interaction with cellular membranes. Graphene's high sensitivity in these applications evolves from the π-carrier cloud confined within an atom-thick layer, quantum-capacitance-induced doping enhancement, closely spaced electronic bands, and a large surface area. We discuss the effect of the electronegativity of the cell wall and the dynamic changes in its chemical potential on doping specific carriers into graphene. Finally, we discuss the challenges and opportunities of graphene-interfaced biocellular systems.