BIOMEDICAL APPLICATIONS I: DELIVERY OF DRUGS - Carbon Nanotubes: From Bench Chemistry to Promising Biomedical Applications - page 26

SWCNTs ~1 nm Nitrene cycloaddition-

substituted C 2 B 9 carborane
units

Boron Boron capture

neutron therapy
(BNCT)

(66)

MWCNTs 10-50

nm

1,3-dipolar cycloaddition of
azomethine ylides

Methotrexate
(MTX)

Cancer therapy (86)

Oxidation and 1,3-dipolar
cycloaddition of azomethine
ylides

Amphotericin B
(AmB)

Fungal infection (87)

SWCNTs ~1 nm Annealing at 350º β -Carotene Photonic tech-

nology

(74)

SWCNTs +
DWCNTs

~2 nm Annealing at 550º + nano-

extraction

Altretamine
(HMM) Cancer therapy (88)

MWCNTs 10-50

nm

Thermal treatment +
Oxidation

Carboplatin Cancer therapy (139)

a Reproduced with permission from G. Pastorin, Pharmaceutical Research 2009 , 26(4),
746-769.”

Another aspect should be also considered for the use of CNTs in drug
delivery. In fact it has been recently demonstrated that they behave like
asbestos, 90 showing carcinogenic effects. Anyway, it should be underlined
that the toxicity of CNTs is still uncertain. All the studies performed till now
are contradictory and not uniform, indicating that several factors related to
both cell lines and materials are involved in the toxicity of CNTs. In fact the
toxicity of CNTs seems to be related to the dimension of the tubes and, most
important, to their functionalisation. 45,90-94 It has been recently observed that
f -CNTs are not toxic, but more studies should be performed to better clarify
this fundamental parameter for considering CNTs an ideal candidate for drug
delivery.
In this chapter we wish to briely summarise the possible approaches for
use of CNTs as DDS and to analyse in more detail the few examples reported
in the literature.

2.2 NONCOVALENT FUNCTIONALISATION ON THE EXTERNAL
WALLS

Functionalisation of CNTs for their application in biomedicine is focused on
the chemical strategies that can render this material biocompatible as well
as functional.