Page 442 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

422 Potential Impacts of Nanomaterials

Using an electrospray technique to generate synthetic nanoparticles
in the range of 8–13 nm with monodisperse aerosol particles of approx-
5 3
imately the same concentration (5
10 cm ), it has been shown that
nano-Cu is a potent inducer in the production of IL-8 in an epithelial cell
line (Cheng 2004). Mice exposed to ion-copper, and to nanoscale (25 nm)
and micro-sized particles of copper via the gastrointestinal tract had
LD50 values of 413 mg/kg, 110 mg/kg, and 5000 mg/kg for nano-copper,
ionic-copper, and micro-copper particles, respectively. Ionic-copper and
copper nanoparticles were moderately toxic whereas copper microparti-
cles were practically nontoxic, accordingly to the Hodge and Sterner
Scale. The kidney of micro-copper exposed mice was similar to control,
but nano-copper exposed mice appeared bronze-colored. Copper micropar-
ticles caused a slight change in spleens compared to controls, but
nanocopper particles (of the similar mass) caused severe atrophy and
color changes of spleens. This suggests that spleen is one of the target
organs for nanoscale copper particles. Viscera (e.g., kidney, spleen, and
liver) of mice exposed to copper nanoparticles were gravely affected. In
addition, nanoparticles induced a dose-dependent change. Pathological
observations were noted in the kidney, especially to the renal proximal
tubules glomeruli lumen of Bowman’s capsules. These changes are typ-
ical of glomerulonephritis. Biochemical parameters (blood urea nitro-
gen [BUN], creatinine–total bile acid [TBA], and alkaline phosphatase
[ALP]) that depict renal and hepatic functions were significantly greater
in nanoparticles-exposed mice than in the controls (Chen et al., 2005).
The great difference in the LD50 of copper nano- and microparticles
is thought to be linked to the difference in the specific areas of these par-
ticles. Indeed, the specific surface areas for the 23.5 nm and 17 µm
5 2 2
copper particles are 2.95
10 and 3.99
10 cm /g, respectively. The
particle number (µ/g) for micro-copper is 44 µ/g, while nano-copper is
10
1.7
l0 µ/g. Compared with the copper microparticles, copper nanopar-
ticles (of the same mass) possess much higher collision probability with
bio-substances in vivo. For the copper nanoparticles, the huge specific
surface area leads to the ultrahigh reactivity.
When copper nanoparticles reach the stomach, they react drastically
+
with hydrogen ions (H ) of gastric juices and can be quickly transformed
into ionic states. This chemical process undoubtedly results in an over-
load of ionic copper in vivo. Finally, it has been shown that kidney, liver,
and spleen are target organs for copper nanoparticles.

Gold Nanoparticles
Many biological applications using gold nanoparticles have emerged
during the last decades. Indeed, these nanoparticles could be used as
transfection vectors (Muangmoonchai et al., 2002; O’Brien et al., 2002;