BIOMEDICAL APPLICATIONS I: DELIVERY OF DRUGS - Carbon Nanotubes: From Bench Chemistry to Promising Biomedical Applications - page 32

Scheme 2.7 MIC of AmB-FITC-functionalised carbon nanotubes on fungi and yeast
after 48 hours of incubation. AmB alone ( AmB ), CNTs alone ( SWNT-NH 3 + ) and CNTs
with AmB covalently bound ( MWNT-AmB and SWNT-AmB ). See also Colour Insert.

Poor or non-existent cellular uptake was observed for large proteins (e.g.,
human immunoglobulin), presumably due to the large size of the cargo or to
ineficient endocytosis of big conjugates. 129

2.5 ENCAPSULATION INSIDE CNTS

As previously mentioned, the use of CNTs to encapsulate molecules has
rendered these nanosystems particularly suitable for additional applications
such as material storage, 72 compound synthesis 73 and drug delivery. 74,88
Successful encapsulation of organic molecules inside SWCNTs has already
been reported (Scheme 2.8). 88,131 - 136 The advantage of this methodology lies in
the ability of CNTs to provide protection and to control the release of loaded
molecules, thus prolonging the effect of eventual drugs.
An interesting example is the incorporation, inside CNTs, of a natural
pigment,

β

-carotene, 74 whose application has been hampered by its fast
degradation, under light exposure. 137,138
From the results obtained in these experiments, the crucial role of carbon
nanotubes in the protection of a natural substance from easy degradation
was obvious, but no details about its delivery were provided.
An interesting encapsulation of a drug inside CNTs has been obtained by
Hampel et al ., who investigated the inluence of CNTs on tumour cell growth. 139
They relied on two main aspects: (i) the incorporation of carboplatin and (ii)
the use of MWCNTs presenting a wider inner diameter. Hence, these types
of tubes determined a higher drug loading that was further increased by
controlled heat. The subsequent cell viability assays revealed that treatment