Environmental Engineering Reference
In-Depth Information
Delay in
growth and
reproduction
Accumulation
in liver,
kidney etc
Lung
inflammation
In vivo
study
Obstruction
in intestine
Mortality
Brain
dysfunction
Fig. 3
Toxic endpoints in in vivo studies that have been observed for ENPs in different
organisms
Physiological adaptation studies revealed decreased levels of unsaturated fatty
acids and increased levels of cyclopropane fatty acids in
P. putida
in presence of
nC60 (Table
5
). Fourier transform infrared spectroscopy (FTIR) data showed a
slightincreaseinphasetransitiontemperature(T
m
) and membrane fluidity of bacte-
rial cells. These changes could be due to the conformational alterations of acyl
chainsatgrowthinhibitingconcentrations(0.5mg/L)ofnC
60
. Increase in the levels
of iso- and aniso-branched fatty acids was observed in
B. subtilis
at a lower concen-
tration(0.01mg/L)ofnC
60
(Fangetal.
2007
). These alterations could result from
the interaction of nC
60
with lipid fractions of bacterial cell membrane and other cel-
lularconstituentstoproducelipidperoxidation.Toxicitystudies(for180days)of
nC
60
on soil microbial community has revealed that nC
60
has less impact on the
bacterialcommunityinnaturalsoils(Table
5
)(Tongetal.
2007
).
E. coli
K12cellsappeartointeractwithSWNTsinsalinesolution(Kangetal.
2007
).A substantial loss in viability of treated cells (79.9ﾱ9.8%) was observed
within60min,comparedtocontrols(7.6ﾱ2.1%)(Table
5
). These results imply that
direct contact between the cell and nanoparticles is needed for inactivation of
E. coli
cells. Moreover, the average percentage of viability loss increases with time. The
authors of this study concluded that the SWNTs exhibit strong antibacterial activity
andcausesirrecoverabledamagetobacterialcells(Kangetal.
2007
).
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