Biomedical Engineering Reference
In-Depth Information
interactions [52]. h ey attached single-stranded DNA oligonucleotides of
dei ned length and sequence to individual nanocrystals, and these assemble
into dimers and trimers on addition of a complementary single-stranded
DNA template. h ey have anticipated that this approach should allow the
construction of more complex two- and three-dimensional assemblies.
Recently, Kang
et al.
have conjugated gold nanoparticles with specii c
peptides and they were successful in selectively transporting them to the
nuclei of cancer cells [53]. Confocal microscopy images of DNA double-
strand breaks showed that localization of gold nanoparticles at the nucleus
of a cancer cell damages the DNA. Gold nanoparticle dark-i eld imaging of
live cells in real time revealed that the nuclear targeting of gold nanopar-
ticles specii cally induces cytokinesis arrest in cancer cells, where binucle-
ate cell formation occurs at er mitosis takes place. Flow cytometry results
indicated that the failure to complete cell division led to programmed cell
death (apoptosis) in cancer cells. h ese results show that gold nanopar-
ticles localized at the nuclei of cancer cells have important implications in
understanding the interaction between nanomaterials and living systems.
Despite the great excitement about the potential uses of gold nanopar-
ticles for medical diagnostics, as tracers, and for other biological applica-
tions, researchers are increasingly aware that potential nanoparticle toxicity
must be investigated before any
in vivo
applications of gold nanoparticles
can move forward [33, 54, 55].
2.4 SilverNanoparticles
Silver nanoparticles have characteristic optical, electrical, and thermal
properties and are being integrated into products that range from photo-
voltaics to biological and chemical sensors. Examples include conductive
inks, pastes and i llers which utilize silver nanoparticles for their high elec-
trical conductivity, stability, and low sintering temperatures. Additional
applications include molecular diagnostics and photonic devices, which
take advantage of the novel optical properties of these nanomaterials. An
increasingly common application is the use of silver nanoparticles for anti-
microbial coatings, and many textiles, keyboards, wound dressings, and
biomedical devices now contain silver nanoparticles that continuously
release a low level of silver ions to provide protection against bacteria.
h e literature describes dif erent methods for obtaining silver nanopar-
ticles, including chemical reduction, solid-state synthesis, sonochemical
synthesis,
in-situ
radical polymerization, and spray pyrolysis [56]. h rough
the optimization of experimental conditions, it is possible to synthesize
