BIOMEDICAL APPLICATIONS I: DELIVERY OF DRUGS - Carbon Nanotubes: From Bench Chemistry to Promising Biomedical Applications - page 33

with free carboplatin resulted in a concentration-dependent decrease in cell
number and an increase in cell apoptosis, with about 50% of cells alive at
a concentration of just 20 μ g/mL. Interestingly, empty CNTs did not affect
cell viability. On the contrary, the addition of carboplatin to empty tubes
determined a synergistic effect, probably because MWCNTs altered the
integrity of the cell membrane and increased the uptake of the drug. These
results suggested that, even though the long-term inluence of CNTs on
cells should be deeply investigated, CNTs seem to be promising carriers
with remarkable mechanical and chemical stability, albeit with still unclear
immunogenic effects.
Scheme 2.8 Anticancer drug hexamethylmelamine (HMM) encapsulated inside
SWCNTs and capped with fullerenes (C 60 ). Reproduced from Ren and Pastorin 88 with
permission. See also Colour Insert.
2.6 CONCLUSIONS AND PERSPECTIVES
Considering the various drug delivery systems that are currently utilised at
the nanoscale, together with the intrinsic properties of CNTs and the various
examples of their applications, we can conclude that CNTs are promising
materials, especially for potential drug delivery and for multimodality cancer
therapy and imaging.
Functionalised CNTs permit incorporating simultaneously several drugs,
targeting agents and even metals (e.g., iron) able to induce hyperthermia
and thus improve therapeutic activities. The great advantage of CNTs is that
they present a reactive external surface, which can be chemically modiied
to improve their role as DDS, and at the same time, their natural huge aspect
ratio allows them to behave like nanoneedles that do not disrupt the integrity
of external membranes during their cellular uptake.