Biomedical Engineering Reference
In-Depth Information
TABLE 8.2 MTT Assay Signals for QD Toxicity to U937 Cells
Cell-QD incubation period
QD, µM
1 h
4 h
24 h
CdSe/ZnS with COOH on the surface
0.025
0.181 ± 0.029
0.185 ± 0.003
0.172 ± 0.035
0.5
0.171 ± 0.033
0.171 ± 0.012
0.165 ± 0.022
2
0.186 ± 0.021
0.150 ± 0.035
0.131 ± 0.007
CuInS2 with COOH on the surface
0.025
0.213 ± 0.052
0.209 ± 0.040
0.237 ± 0.011
0.05
0.213 ± 0.051
0.215 ± 0.009
0.205 ± 0.007
1.25
0.239 ± 0.030
0.273 ± 0.026
0.210 ± 0.011
Control
None
0.246 ± 0.004
0.220 ± 0.025
0.232 ± 0.051
8.2.2.2 Procedure for the Evaluation of QD Toxicity to U937 Cells
using the DAPI Staining and Cell Count Method
In order to have a better idea of the toxic effects of QDs on cells, an alternative
strategy that involves actual counting of cells, both viable and non-viable, can be
used. Using (4',6-diamidino-2-phenylindole) DAPI stain, the dead cells absorb
the dye whereas live cells do not. Briefly, the assay is performed as follows.
(1)
Grow the cells on a glass cover slip inserted in a 6-well plate until they are
30-50% confluent.
(2)
Replace the medium with a new medium to which the NPs are mixed to
attain the desired NP concentrations.
(3)
Incubate the plates for 24 h at 37 °C and 5% CO
2
.
(4)
Remove the medium with NPs.
(5)
Add 1 mL of 1× DPBS to each well to wash the cells.
(6)
Repeat the washing 2 more times.
(7)
Add 1 mL of 1× DPBS to each well.
(8)
Add 50 uL of DAPI solution.
(9)
Incubate at 37 °C and 5% CO
2
for 5 min.
(10)
Remove the DPBS with DAPI.
(11)
Rinse the cells with 1× DPBS.
(12)
Place 500 uL 1× DPBS and scan the cells under the microscope.
