In this review, two different families of C NPs depending on the
content of carbon atoms are addressed. On the one hand, a first group
is composed by nanostructures of low-carbon content involving a
variety of polymeric and molecular nanoparticles as well as
nanocellulose (NC). Herein we only address NC for being involved
in the context of the review. Those nanosized cellulose fibrils bearing
multiple hydroxyl groups display a strong tendency to intramolecular
hydrogen bonds. On the other hand, a second group of high
carbon-content nanostructures is discussed; according to their structure
and carbon hybridation, a new family of carbon nanoallotropes
can be classified into fullerenes, spherical nanodots, carbon
nanotubes, graphene nanoparticles and other nanostructures
(nanodiamonds, nano-onions, nanohorns, nanocones amongst
others). Those carbon nanoparticles exhibit particular electrical, mechanical,
optical and chemical properties by virtue of the variety
of sizes and shapes achieved depending on the carbon arrangement
in sp2 and/or sp3 hybrid networks. Nowadays, despite the
fascinating properties of such carbon nanostructures, only few applications
have been discovered so far; we just scarcely scrapped
along the iceberg of opportunities.