Biomedical Engineering Reference
In-Depth Information
human health. To date, we have barely scratched the lessons to learn and to
comprehend the effects of these tiny molecules on cells, tissues, and whole
organisms. This chapter will focus on the current knowledge of nanotoxicity
and highlight areas where new information is available and suggest directions
for additional and future research.
To complete existing knowledge about the interactions between the NMs
and the biological systems, nanotoxicology deals with the study of their toxic
or biological effects. Because NMs belong to a new class of materials, prog-
ress in this new discipline relies largely on developing methodology to char-
acterize NMs in biological samples, quantify them in living systems, study
their uptake, translocation, biodistribution, accumulation, and chemical status
in vitro and in vivo. In addition, the biochemical pathways and biomolecules
that are directly or indirectly affected by their presence in a living system need
to be established both short term and long term in order to understand pos-
sible consequences when they are used for medical applications. Appropriate
analytical techniques and their application to the study of the toxicological
activities of NMs need to be developed to provide appropriate and powerful
means for characterizing the toxic effects or biological behaviors in biological
systems.
Nanotoxicology addresses the toxicology profiles of NMs which appear to
have unusual toxicity effects that are not observed with larger particles. The
NMs of interest in this topic are those which are deliberately produced for medi-
cal applications such as engineered carbon nanotubes,
1-3
quantum dots (QDs),
4-14
iron oxide magnetic nanoparticles (IOMNPs),
4,15-17
liposomes,
18-26
titanium
oxide,
27
and many more. A few of these NMs such as gold,
28
silver,
29-31
titanium
dioxide, alumina, metal oxides, liposomes, polymers,
32
and carbon nanotubes
33
have been studied in terms of toxicity in a limited manner. Some NMs exhibit
size-dependent pathogenic effects that are different from larger particles.
29
NMs
have larger surface area to mass ratios which may be responsible for the ease of
penetration of the cells and tissues or cells that in some cases may lead to the
release of immune response.
14,34-39
Some NMs exhibit the ability to translocate
from solution into cells
14
or even transcend the blood brain barrier.
40
This accel-
erated the studies on nanoparticle toxicology study in the brain, blood, liver,
skin, and gut.
The rapid growth of medical applications of NMs calls for concerns about
the potential health and environmental risks related to the use and widespread
production required by the demands to support this outburst in nanotechnol-
ogy. Multiple areas of concern related with the usage of NMs including the
deposition and clearing, biocompatibility, systemic translocation, and body dis-
tribution of NMs, intestinal tract involvement, and direct effects on the central
nervous system have been studied so far.
41
The different physico-chemical and
structural properties of NMs that result from their nanoscale size can be sued
to account for a number of material interactions that can lead to toxic effects.
42
Studies have shown that NMs can have pronounced environmental effects even
