OVERVIEW ON THE MAJOR RESEARCH ACTIVITIES ON CARBON NANOTUBES BEING DONE IN AMERICA, EUROPE AND ASIA - Carbon Nanotubes: From Bench Chemistry to Promising Biomedical Applications - page 280

The identiication method was validated in vitro by demonstrating the
detection of six genotoxic analytes. Results showed that chemotherapeutic
alkylating agents were detected immediately upon exposure to the
SWCNT-DNA complex. Emission red shifts of up to 6 meV and concomitant
attenuation were observed using NIR spectroluorimetry. Hydrogen peroxide
was detected by the SWCNT-DNA complex through attenuation of both (6, 5)
and (7, 5) luorescence bands to similar extents with slight shifting of peak
wavelengths ( Fig. 9.22c) . Singlet oxygen induced a pronounced redshift in
(6, 5) nanotube emission with virtually no (7, 5) nanotube shift (Fig. 9.22d),
as conirmed by a three-dimensional photoluminescence proile. In addition,
exposure to the singlet oxygen scavenger sodium azide signiicantly reduces
the magnitude of the (6, 5) band shift. Finally, it was possible to detect these
analytes in real time within live 3T3 cells, demonstrating multiplexed optical
detection from a nanoscale biosensor and the irst label-free tool able to
optically discriminate among several short-living agents.
In another study, the authors evaluated the in vivo pharmacological
effects on the immune response deriving from the individual, simultaneous
or sequential delivery of dexamethasone (DX) and vascular endothelial
growth factor (VEGF). 138 For the irst time, imaging of a SWCNT luorescence
device implanted subcutaneously in a rat was monitored, together with the
localisation of the vascular network formed around the hydrogel-coated,
microcapillary implant of SWCNTs. For tissue response studies, the chick
embryo chorioallantoic membrane (CAM) was used as a tissue model for
an 8-day implantation period. The average vascular density of the tissue
surrounding the sensor with simultaneous, sequential or no delivery of DX
and VEGF was 1.24 ± 0.35 × 10 -3 vessels/μm 2 , 1.15 ± 0.30 × 10 -3 vessels/
μm 2 and 0.71 ± 0.20 × 10 -3 vessels/μm 2 , respectively. Calculations of the
therapeutic index (i.e., vasculature/inlammation ratio), which relects
promotion of angiogenesis versus the host immune response, demonstrated
that sequential DX/VEGF delivery was 60.3% and 139.3% higher than that
of VEGF and DX release alone, respectively, and was also 32.1% higher when
compared with simultaneous administration, proving to be a more effective
strategy in optimising the delivery of pharmacologically active molecules.
The adsorption of several species on the surface of CNTs is often
associated with an irreversible interaction, which is at the basis of electronic
sensors or thin-ilm transistors although without a clear mechanism. In
order to have a better understanding of the process involved, the research
group investigated the reversible adsorption of thionyl chloride (SOCl 2 )
via non-covalent functionalisation with molecules bearing free amino-
groups. 139 The evaluation of 11 of such molecules demonstrated that the
analyte (SOCl 2 ) adsorption is deeply affected by the basicity (expressed
as pKb of the base or as pKa of its conjugated acid) of the groups at the
surface. More precisely, only the amine-containing molecules with pKa <