Biomedical Engineering Reference
In-Depth Information
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, progress
in this new discipline relies largely on developing methodology to characterize
NMs in biological samples, quantify them in living systems, study their uptake,
translocation, biodistribution, accumulation, and chemical status in vitro and in
vivo. 18,24,31,33,134,144,146,186,201,246,322,323,328,329,331,333-335,337,340-342,349,419 In addi-
tion, 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 possible 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 devel-
oped 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 medical
applications such as engineered CNTs, QDs, iron oxide magnetic nanoparticles,
liposomes, titanium oxide, and many more. A few of these NMs such as gold,
silver, titanium dioxide, alumina, metal oxides, liposomes, polymers, and CNTs
have been studied in terms of toxicity in a limited manner. Some NMs exhibit
size dependent pathogenic effects that are different from larger particles. NMs
have larger surface area to mass ratios which may be responsible for ease of pen-
etration of cells and tissues or cells that in some cases may lead to the release of
immune response. 18,44,144,146,186,188,332-335,345,420,421,423,424 Some NMs exhibit the
ability to translocate from solution into cells or even transcend the blood brain
barrier. 238,426 This accelerated the studies on nanoparticle toxicology study in
the brain, blood, liver, skin, and gut. 58,72,88,91,128,161,169,289,297,307,313,346,351-353,427
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 nanotechnology.
Multiple areas of concern related with the usage of NMs including the deposi-
tion and clearing, biocompatibility, systemic translocation and body distribution
of NPs, intestinal tract involvement, and direct effects on the central nervous
system have been studied so far. The different physicochemical 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. Studies have
shown that NMs can have pronounced environmental effects even at very low
aqueous concentrations. 113 As an example, the use of CdSe QDs in humans may
be limited because these contains the heavy metals cadmium which are report-
edly toxic to cells at concentrations as low as 10 u g/mL. 12,14,18,129,134,144,201,20
2,332 The various properties of the QD such as its size, charge, concentration,
capping material, functional groups, and mechanical stability have been studied
as possible determining factors in toxicity.
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