Page 435 - Book Hosokawa Nanoparticle Technology Handbook

7.3 SAFETY OF NANOPARTICLES FUNDAMENTALS
shape after electrophoresis, and the tales of comets quantum dots does not show DNA damage. This is
cannot be observed [13–16]. probably because the DNA damage has been repaired
Fig. 7.3.8 shows the results of the experiments with during the longer cultivation time.
quantum dots conjugated with COOH (both purified Fig. 7.3.9 shows the results of DNA damage. The
and unpurified) to WTK-1 cells, a human lym- nanoparticles have been purified over and over again
phoblast mutation strain [17]. The vertical axis shows in order to get rid of impurities derived from the
the lengths of the tails, and the horizontal axis the process of the surface-conjugation. The concentra-
5
concentrations of the quantum dots. The concentra- tions are from 0.5 to 2 M for 10 cells. The cultiva-
tion of the nanoparticles is 2 M. tion time after the addition of the nanoparticles is
The results are as follows: the unpurified quantum 24h. Hydrogen peroxide (aqua) is used as the positive
dots with COOH caused damage to DNA. On the control. The results show; DNA damage is not
other hand, the electrophoresis with the purified observed up to 2 M. The same experiment was

45 90
Purified nanoparticle by the column 80 Melcapto undecanic acid
40 Unpurified nanoparticle 70 Organic amine
Comet length ( M) 35 Comet length ( M) 50 TOPO
Glycerol
60
ZnS
40
30
30
20
25
10
20 0
0 0.5 1 2 4 0 25 50 100 200 400
Concentration of tested compounds ( M) Concentration of tested compounds ( g/ml)

Figure 7.3.8
Cyto-toxicity of nanoparticles by the Comet Assay.

Figure 7.3.9
Microscopic study for the Comet Asssay and the estimation of the cyto-toxicity.

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