Ecotoxicology of Manufactured Nanoparticles - Environmental and Human Health Impacts of Nanotechnology - page 277

(a)

(b)

Figure 7.9 Uptake of nanoparticles by aquatic organisms. (a) Left: Silver nanoparticles in
the membrane and inside of an Escherichia coli cell; right: EDS elemental mapping showing
silver distribution through the sample. (b) Daphnia magna exposed to 5 mg/l of lipid coated
single-walled nanotubes showing large numbers of tubes fi lling the gut track (1 h exposure)
and clumps of precipitated tubes around the daphnid (20 h) (bar = 200 m). ((a) Reprinted

with permission from J. R. Morones, J. L. Elechiguerra, A. Camacho et al. (2005) The bacte-
ricidal effect of silver nanoparticles, Nanotechnology , 16 , 2346-53. Copyright 2005 Institute
of Physics. (b) Reproduced with permission from A. P. Roberts, A. S. Mount, B. Seda et al.
(2007) In vivo biomodifi cation of lipid-coated carbon nanotubes by Daphnia magna,
Environmental Science & Technology , 41 , 3025-9. Copyright 2007 American Chemical
Society.) (See colour plate section for a colour representation)

µ

copper nanoparticles (Griffi tt et al. , 2007) but it is unclear if these effects are related
to the direct accumulation of nanoparticles in the gill tissue.

7.3.3.2 Release of Toxic Dissolved Species

As noted in Section 7.2.2, metal-containing nanoparticles may exert toxic effects
by dissolution of their component metals. Slowly dissolving nanoparticles may
present a localised ' point source ' of high concentrations of dissolved metals. Cells
in close proximity to such particles will experience a much higher dose of metal
than is suggested by the bulk solution dissolved metal concentration (Figure 7.6).