Biomedical Engineering Reference
In-Depth Information
TABLE 3.7
Studies on Toxicity Due to Different Structural Arrangement
Type of Nanoparticle
Toxicity/Organ Affected
Mechanism Involved/Results
Reference
TiO
2
nanoparticle
Cytotoxicity and
genotoxicity
The anatase crystal form may be
more toxic because of its
greater oxidizing potential,
which would generate a greater
amount of reactive species.
Jiang et al. (2008)
Carbon nanotubes
MWCNTs
Apoptosis
human T cells
The cytotoxicity of pristine
versus oxidized MWCNTs was
compared and found that
oxidized MWCNTs induced
greater human T cell apoptosis.
Bottini et al. (2006)
TiO
2
nanoparticle
Necrosis
Anatase form of TiO
2
nanoparticles causes greater
toxic response compared to the
rutile form, especially in the
viable cells. It caused increased
levels of various inflammatory
indicators like LDH and IL-8,
which may be because of its
greater oxidizing potential in
generating ROS.
Braydich-Stolle et al. (2009)
Jiang et al. (2008)
Wu et al. (2010)
TiO
2
nanoparticles
Cytotoxicity/dermal
fibroblasts and human
lung epithelial cells
Photoactivation of anatase TiO
2
will increase cytotoxicity but
concentrations over 100 mg/mL
will be significant enough to
cause any ill effects.
Sayes et al. (2006a,b,c)
Warheit et al. (2006)
Rutile nano TiO
2
Pulmonary inflammatory
response from 20 nm TiO
2
Rutile nanoparticles of 20 nm
TiO
2
causes pulmonary
inflammatory response in
THP-1 and A549 cell line.
Chen et al. (2006a)
100-200 nm (Takenaka et al. 2001; Oberdörster et al. 2005). At high concentrations, nanoparticles
would allow particle aggregation (Churg et al. 1998; Gurr et al. 2005) and, therefore, reduced toxic
effects as compared to lower concentrations (Takenaka et al. 2001) as observed in Table 3.10. The
majority of aggregates have a size >100 nm, that is, a size that seems to be a threshold for many of
the adverse health effects of small particles. Therefore, nanoparticles at high concentrations will
lead to the formation of aggregates that may not be as toxic as lower concentrations of the same
nanoparticles.
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Smaller nanoparticles (<100 nm) cause more adverse respiratory health effects (inflammation) than
larger particles of the same material (Ferin et al. 1992; Oberdörster et al. 1994, 2005; Wilson et al.
2002; Donaldson and Stone 2003; Gurr et al. 2005) as mentioned in Table 3.11. This was proven by
the inhalation and instillation (Oberdörster et al. 2005) of 20 and 250 nm diameter TiO
2
particles
in the rat (with the same crystalline structure). The results showed that smaller particles led to a
persistently high inflammatory reaction in the lungs as compared to larger sized particles. In the
postexposure period (up to 1 year), it was observed that the smaller particles had, (1) a significantly
prolonged retention, (2) an increased translocation to the pulmonary interstitium and pulmonary
