Biomedical Engineering Reference
In-Depth Information
Fig. 1 TEM images of plasmonic gold nanostructures: (a) nanospheres, (b) nanorods, and
(c) nanoshells. (Figure adapted from [
6
])
The objective of nanotechnology is to detect every cancer cell instead of full grown cancers
(Ranu K. Dutta).
Nanoparticles play a very important role in cancer research. Due to their
extremely small size, nanoparticles are easily and more readily taken up by the
human body. Hence, they can interact well with biological membranes so that cells,
tissues, and organs are eligible for entrance of nanoparticles [
7
]. Nanoparticles are
used in the field of medicine for several reasons: (1) improved delivery of poorly
water-soluble drugs, which enhances their faster dissolution in the blood stream;
(2) transcytosis of drugs across tight epithelial and endothelial barriers; (3) delivery
of large macromolecule drugs to intracellular sites of action; (4) co-delivery of two
or more drugs or therapeutic modality for combination therapy; (5) visualization of
sites of drug delivery by combining therapeutic agents with imaging modalities;
and (6) Conjugating nanoparticles with site specific ligands can be useful in site
specific imaging, image guided therapy, for specific MRI contrast agents, ablation,
hyperthermia, etc.
2 Properties of Nanoparticles
The size of nanoparticles lies between that of bulk material and the atomic
structures, which gives them unique properties and makes them eligible candidates
for several applications. At the nanoscale, the percentage of atoms present at the
surface of a material becomes significantly enhanced, resulting in drastically
changed properties of these nanomaterials. For bulk materials larger than 1
m
m
(1 micron), the percentage of atoms at the surface is insignificant in relation to the
number of atoms present in their nanoform. At the small size range (
10 nm) the
concept of quantum confinement originates. The wave function associated with
these materials will be confined and degenerate, resulting in strong quantum
confinement. Several varieties of nanoparticles are available, such as polymeric
nanoparticles, dendrimers [
8
-
10
], metal nanoparticles, quantum dots (QDs),
<
