Biomedical Engineering Reference
In-Depth Information
carboxylic acid, polyhydroxyl group, amphiphilic polymers to increase the
hydrophilicity.
Fullerenes and their derivatives show potential antiviral activity. The
antiviral activity of fullerene derivatives is based on several biological
properties, including their molecular architecture and antioxidant activity.
Another potential medical application of fullerenes is related to their photo-
excitation. In fact, fullerene can be excited from ground state to
1
C60 by
photo-irradiation. In the presence of molecular oxygen, the fullerene can
decay from its triplet to ground state, transferring its energy to O
2
, gen-
erating a single oxygen
1
O
2
, and is highly cytotoxic. Again, in the presence
of oxygen, the fullerene radical anion can transfer one electron, produc-
ing a superoxide anion radical O
2
×
-
and an hydroxyl radical ×OH [156].
Iwamoto and Yamakoshi [157] introduced a highly water soluble C60-N
vinylpyrrolidine copolymer as agent for photodynamic therapy. Liu et al. [158]
demonstrated the use of a poly-ethylene glycol (PEG)-conjugated fullerene
containing Gd
3+
ions for photodynamic therapy in combination with MRI.
The authors demonstrate through experimental data, that tumor PDT effect
was significantly promoted by photosensitizer tumor targetability and MRI
activity. By attaching hydrophilic moieties, fullerenes become water-soluble
and are capable of carrying drugs and genes for cellular delivery. A lipophilic
slow-release drug delivery system which employs fullerene derivatives to en-
hance therapeutic efficacy in tissue culture, was designed by Zakharian et al.
[159]. So modified fullerenes have the potential to provide a significant anti-
cancer activity in cell culture, as demonstrated with C60-paclitaxel conjugate.
Research continues into ways to increase the solubility of fullerenes and to
investigate the toxicity of fullerenes and their derived compounds.
5.9 Peptides nanoparticles
Peptides that specifically interact with receptors over-expressed by cancer
cells have been successfully developed as targeting molecules for drug deliv-
ery and in vivo imaging [160]. The interaction of peptides and proteins with
the cell membrane results in their penetration into the cell, or the formation
of pores within the cell membrane. Because of their ability to target and
enter cells, peptide and protein carriers hold great potential for the deliv-
ery of genes and antisense oligonucleotides to cancer cells [160]. Bombesin
(BBN) peptide and its analogs can be used to target gastrin-releasing pep-
tide (GRP) receptors. Thus, in vivo
GRP receptors are over-expressed in
GBM, small cell lung, gastric, pancreatic, prostate, breast, cervical, and co-
lon cancers. Recently, GNPs functionalized by a high load of thioctic acid-
bombesin peptide were used to target prostate tumor xenografts in SCID
mice. Using normal and prostate tumor-bearing mice, they showed that
this compound exhibits a high binding affinity to the tumor, and confirmed
that these constructs are GRP receptor specific and accumulate with high
selectivity in GRP receptor-rich pancreatic acine [161]. Fibroblast growth
