  The scientific community has witnessed an exponential increase in the
applications of graphene and graphene-based materials in a wide range of
fields. For what concerns neuroscience, the interest raised by these materials
is two-fold. On one side, nanosheets made of graphene or graphene derivatives
(graphene oxide, or its reduced form) can be used as carriers for drug
delivery. Here, an important aspect is to evaluate their toxicity, which
strongly depends on flake composition, chemical functionalization and
dimensions. On the other side, graphene can be exploited as a substrate for
tissue engineering. In this case, conductivity is probably the most relevant
amongst the various properties of the different graphene materials, as it may
allow to instruct and interrogate neural networks, as well as to drive neural
growth and differentiation. In this review, we try to give a comprehensive view
of the accomplishments and new challenges of the field, as well as which in our
view are the most exciting directions to take in the immediate future. These
include the need to engineer multifunctional nanoparticles able to cross the
blood-brain-barrier to reach neural cells, and to achieve on-demand delivery of
specific drugs. We describe the state-of-the-art in the use of graphene
materials to engineer three-dimensional scaffolds to drive neuronal growth and
regeneration in vivo, and the possibility of using graphene as a component of
hybrid composites/multi-layer organic electronics devices. Last but not least,
we address the need of an accurate theoretical modeling of the interface
between graphene and biological material, by modeling the interaction of
graphene with proteins and cell membranes at the nanoscale, and describing the
physical mechanism(s) of charge transfer by which the various graphene
materials can influence the excitability and physiology of neural cells.
