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.