Chemistry Reference
In-Depth Information
Se
Se
Pt
4+
Se
Se
Pt
4+
Cl
Cl
Cl
Cl
19
O
H
H
H
O
H
N
H
H
H
H
20
O
N
N
O
O
N
O
O
O
Gd
N
O
OH
n
O
12
H
O
N
O
H
n
21
O
x
O
22
O
Fig. 8 Structures of DNA-cleaving and fullerene-polymers for PCT
[
105
]. Interestingly, the polycarbonate endowed with the fullerene derivative
behaved better than that functionalized with fullerene itself. Very recently the
same synthetic protocol has been used in order to prepare fullerene-functionalized
polysulfones 18 [
106
]. These materials show not only a very high thermal stability
and glass transition temperatures depending on the C
60
content, but also optical
limiting properties.
On the other hand, it is well known that fullerene may act as a scavenger. When
excited in the ultraviolet region (340-400 nm) it generates reactive oxygen species
(ROS) acting as an effective photosensitizer, also useful in the visible-light cleav-
age of DNA in the photodynamic cancer therapy (PCT) [
107
]. However, in order to
be successfully employed C
60
needs to be transformed in a water-soluble derivative
and, among other things, its incorporation in hydrophilic polymers proved to be an
excellent opportunity. In this regard, different polyfullerenes have been tested as
DNA cleavers such as the supramolecular polymer 19 [
108
] formed by fullerene
units complexed within the upper rims of cyclodextrin dimers (Fig.
8
).
Cyclodextrins were also employed in order to afford water solubility to the main
chain polymer 20, formed through nucleophilic polyaddition reaction between C
60
and the
ʲ
-cyclodextrin-bis(
p-
aminophenyl) ether [
109
]. Once again, under visible
light conditions 20 proved to be a highly efficient DNA-cleaving agent for
oligonucleotides. More recently a photosensitizer with magnetic resonance imaging
(MRI) activity has been achieved by linking polyethylene glycol to fullerene at
one end and the diethylenetriaminepentaacetic acid Gd
3+
complex at the other
