Biomedical Engineering Reference
In-Depth Information
properties. A colloid refers to a substance in which many fine particles are
suspended in a stable condition with another substance. Gold nanoparticles
were traditionally used in the Indian remedy “curcumin.”
6
The German bac-
teriologist Robert Koch showed that gold compounds inhibit the growth of
bacteria. He was awarded the Nobel Prize for medicine in 1905.
With the developments in the pharmaceutical industry, first in 1935, gold
salt-containing drugs were reported to be effective for the treatment of rheu-
matoid arthritis. It is thought that gold affects the entire immune response
(phagocytes, leukocytes, T cells) and reduces its potency and limits its oxi-
dizing nature on joint inflammation and erosion. This effect is explained by
the fact that administered gold compounds accumulate within the body once
absorbed into the cells and are linked to antimitochondrial activity, inducing
the apoptosis of proinflammatory cells. The World Health Organization clas-
sified gold salt-containing compounds as antirheumatic agents and included
such compounds in the basic treatment scheme of the disease.
Because of the long history of the use of gold inside the body, the safety
issues seem to have been somewhat easier to assume, despite becoming more
and more challenging owing to achievements in the synthesis of new materi-
als enabled by nanotechnology.
The properties of gold molecules processed to nanometer dimension are
thoroughly studied. Gold attains divergent physical and chemical charac-
teristics while its molecules are being processed to nanoscale dimension.
Scientists have revealed the diverse properties of nanoparticle gold, which
is dependent on various factors. Particularly, such properties are dependent
not only on the size of the gold nanoparticle but also on other characteristics
such as particle shape, charge and composition, or surface coating, which are
also important. Consequently, the health monitoring aspects are of greater
concern than before.
When dealing with constraints of size <100 nm, the laws of quantum
physics supersede those of traditional physics, resulting in changes in a sub-
stance's properties. Quantum size effects begin to significantly alter material
properties, such as transparency, color of fluorescence, electrical conductiv-
ity, magnetic permeability, and other characteristics. All these properties are
of great interest for the industry and society, as they enable new applica-
tions and products. Consequently, more attention is focused on determining
the ratio of efficiency versus toxicity, or harm versus benefit. There are some
examples of conventional use of nanoscaled gold particles. For instance, the
Japanese scientist Dr. Masatake Haruta discovered that while the particle
diameter is turned in the size range of 3-5 nm, gold exhibits unique cata-
lytic performance, for example, carbon monoxide (CO) oxidation and direct
peroxide (H
2
O
2
) production at a temperature as low as -77°C.
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In practice,
this invention was tested to prevent bad odor in rest rooms and are already
in use in Japan. Thus, gold nanoparticles can eliminate odors produced by
bacterial action. This is an unusual feature for bulk gold but characteristic for
