3.4.2 Bioimpedance phase of the HUVECs on the collagen thin
films
Fig. 6 (D-F) shows the phase diagrams of the measured bioimpedance of
the cultured HUVECs on the collagen thin films with different
concentrations during the time. The obtained results were consistent
with the results of the MSCs. As shown in the figure, for all
concentrations of the collagen thin films, the impedance phase has
become more negative over time, indicating the attachment and growth of
cells over time. The lower the concentration of the collagen thin films,
the greater the amount of this negativity, indicating the greater number
of the cells inside the wells. Further negation of the impedance phase
over time indicates that the number of cells has increased. Also,
similar to the MSCs, the cells cultured on the collagen thin films with
lower concentration, has more negative differential phase, which
indicates that the proliferation rate of the cells on the low
concentration collagen thin films is higher respect to the cells
cultured on the collagen thin films with higher concentrations.
Conclusion
In this paper, a bioimpedance sensor was used to measure the impedance
behavior of the biological cells cultured on a scaffold of collagen thin
films. The collagen thin films were formed on the 1-hexadecanethiol
modified surface of the interdigitated electrodes. Collagen thin films
are beneficial to direct a variety of biological issues such as cell
morphology, cell proliferation, cell migration, and the effect of
surface characteristics on the cellular behaviors. Three different cell
lines, the MSCs, the MDA-MB-231, and HUVECs were seeded on the collagen
thin films with various concentrations. The interaction and the
proliferation rate of these cells were investigated by the microscopic
and impedance approaches. Results showed that the MDA-MB-231 cells did
not attach to the collagen thin films and died. In general, cancerous
cells produce collagenase, which is an enzyme that dissolves and
destroys collagen. It seems since these collagenases exist in breast
cancerous cells, they can destroy the collagen thin films and
consequently, the appropriate bed for cell attachment is destroyed. By
destroying these collagen thin films, the cells do not find a proper
substrate to adhere and die.
The MSCs, and HUVECs excellently adhered to the collagen thin films and
were investigated by microscopic and impedance methods. Impedance
magnitude and phase illustrated that the proliferation rate of both
MSCs, and HUVECs increased by reducing the collagen thin films
concentrations.