Biomedical Engineering Reference
In-Depth Information
factor-induced angiogenesis in retinal endothelial cells. Alteration of the
permeability barrier integrity plays a major role in drug-based therapies, as
well as the pathogenesis of cardiovascular diseases, inflammation, acute lung
injury syndromes, and carcinogenesis. Recently the molecular mechanism
of SNPs on VEGF-and IL-1b-induced retinal endothelial cell permeability
has been evaluated. Both VEGF and IL-1b increase endothelial cell perme-
ability via an Src dependent pathway. SNPs were found to block VEGF and
IL-1b-induced permeability in retinal endothelial cells from porcine retina,
and this inhibitory effect was dependent on the modulation via Src phos-
phorylation at Y419 [133]. A novel study has demonstrated the antitumor
activity of biologically synthesized SNPs in a Dalton's lymphoma ascites tu-
mor system in vitro, by activation of the caspase 3 enzyme which is known
to have a potent inhibitory effect on disease progression in a mouse model,
leading to a potent restorative effect in the treated tumor volume [134].
5.5 Metal oxide
Titanium dioxide (TiO
2
) is a semiconductor, well-known as a ultraviolet
light (UV)-inducible catalyst in the photooxidation of organic substrates
and the deactivation of bacteria, algae, and viruses [135-136]. Under UV
excitation, TiO
2
NPs of various sizes and morphologies have been reported
to exhibit cytotoxicity toward some tumors [137-138]. One recent example
[137] describes 50 nm rhodamine-labeled TiO
2
/PEG constructs able to be
internalized into rat glioma C6 cells. The antitumor performance was evalu-
ated in glioma cell spheroids representing a provisional three-dimensional
model valuable for translation to animal xenografted models. The cytotoxic
effect of the UV-irradiated photocatalyst depended on the concentration
of TiO
2
/PEG and the light exposure time. More than 90% of cells were
killed by a UV dose of 13.5 J cm
−2
in the presence of the nanocatalyst at a
concentration of 0.5 mg/mL. Moreover, fluorescent images of the photo-
catalyst-treated spheroids co-stained with apoptosis and necrosis markers,
Annexin V-FITC and propidium iodide, reveal the prevalence of induced
apoptotic cell death within first 6 hours. Functionalization of 5 nm high
crystallinity TiO
2
NPs with a monoclonal antibody recognizing IL13R fos-
tered nanoparticle delivery specifically to GBM cells in a manner dependent
upon cellular membrane IL13R expression. The direct visualization of the
TiO
2
-antibody/receptor interaction and mapping of the IL13R location
and distribution throughout a single A172 brain cancer cell was demon-
strated using synchrotron-based X-ray fluorescence microscopy [139-140].
It is well established that UV-photoexcitation of bare TiO
2
particles in
aqueous solution results in the formation of various ROS, mainly hydroxyl
(OH), peroxy (HO
2
) radicals, and singlet oxygen (
1
O
2
) [141]. However, in
the case of DA- and DA-antibody-modified TiO
2
particles, ROS arise from
multiple, mechanically distinct redox chemistries, and the principal ROS
produced is the superoxide anion, formed by reaction of photogenerated
