Figure 5. Distribution of glioma cells in the microchannel
according to applied DEP forces. Numbers and positions of glioma cells
associated with a) strong pDEP, b) pDEP, c)weak pDEP forces. Ordinary one-way ANOVA Tukey’s multiple comparison
test was applied using GraphPad Prism 9. *p ≤ 0.05, **p ≤ 0.01, ***p ≤
0.001, ****p ≤ 0.0001.
The results showed that U87 glioma cells experienced clear pDEP behavior
between the frequencies of 200 kHz and 10 MHz, as shown inFigure 4. The crossover frequency for the U87 glioma cells were
almost 140 kHz. However, the U87 glioma cells did not exhibited clear
nDEP response based on our observations, see Supplementary
Materials Video S1 . Hence, we performed dielectrophoretic
characterization of U87 glioma cells using 3 Vpp, 200
kHz to 10 MHz. Figure 4a displays the number of cells those
were positioned according to strength of the DEP forces generated by
varying frequencies. The number of cells experienced strong pDEP
behavior was 50% of the population. This subpopulation of glioma cells
became distinguishable at 200 kHz. Figure 4b-4d show the number
of glioma cells with pDEP behavior when 3 Vpp, and
frequencies varying between 0 – 10 MHz was applied.
Figure 6 presents the viability of the U87 glioma cells. First,
we confirmed viability of the cells using Student’s t-test. The
difference in viability was not significant for the cells in regular
growth medium and low-conductive DEP buffer (p = 0.256,Supplementary Document ). Next, we stained the cells with DAPI
and PI dyes before introducing the cells into the DEP chip and obtained
3.08 % PI-positive cells in the cell population. Afterwards, we
determined the number of PI-positive cells upon the DEP experiment that
was performed in 10 minutes. We observed 2.06% increase in the number
of PI-positive cells in the microfluidic channel.