Abstract:Confidence and integrity are critical in the physical and chemical analyses of tissues and living cells. However, many of the probes targeting biological markers for confocal spectroscopy affect cells’ molecular identity. Hence, we combined photonics with electrical analysis in an assisted laser impedance spectroscopy facility and applied it to characterize two breast cancer cell lines (BT-474 and MCF-7) and lymphocytes (as a normal control). The setup comprised a sample holder with a ∼15 000 cell capacity fit… Show more
“…Since cell membranes, ideally modelled as capacitors, include a lipid bilayer, surface roughness, and integrated ion channels that resemble a porous surface contact, the capacitance was modulated by the charge transfer and differs from the capacitance of an ideal capacitor (i.e., frequency-dependent) [39,40]. Therefore, the R CT and CPE series group is describing the transport phenomena near the electrodes [40][41][42] (i.e., the charge transport through the electrode/electrolyte interface including the cells membrane capacitance (electrode-cells-suspension medium assembly)).…”
Section: Interpretation Of Measured Impedance Data By Equivalent Circuitmentioning
Here, we reported a study on the detection and electrical characterization of both cancer cell line and primary tumor cells. Dielectrophoresis (DEP) and electrical impedance spectroscopy (EIS) were jointly employed to enable the rapid and label-free differentiation of various cancer cells from normal ones. The primary tumor cells that were collected from two colorectal cancer patients and cancer cell lines (SW-403, Jurkat, and THP-1), and healthy peripheral blood mononuclear cells (PBMCs) were trapped first at the level of interdigitated microelectrodes with the help of dielectrophoresis. Correlation of the cells dielectric characteristics that was obtained via electrical impedance spectroscopy (EIS) allowed evident differentiation of the various types of cell. The differentiations were assigned to a “dielectric phenotype” based on their crossover frequencies. Finally, Randles equivalent circuit model was employed for highlighting the differences with regard to a series group of charge transport resistance and constant phase element for cancerous and normal cells.
“…Since cell membranes, ideally modelled as capacitors, include a lipid bilayer, surface roughness, and integrated ion channels that resemble a porous surface contact, the capacitance was modulated by the charge transfer and differs from the capacitance of an ideal capacitor (i.e., frequency-dependent) [39,40]. Therefore, the R CT and CPE series group is describing the transport phenomena near the electrodes [40][41][42] (i.e., the charge transport through the electrode/electrolyte interface including the cells membrane capacitance (electrode-cells-suspension medium assembly)).…”
Section: Interpretation Of Measured Impedance Data By Equivalent Circuitmentioning
Here, we reported a study on the detection and electrical characterization of both cancer cell line and primary tumor cells. Dielectrophoresis (DEP) and electrical impedance spectroscopy (EIS) were jointly employed to enable the rapid and label-free differentiation of various cancer cells from normal ones. The primary tumor cells that were collected from two colorectal cancer patients and cancer cell lines (SW-403, Jurkat, and THP-1), and healthy peripheral blood mononuclear cells (PBMCs) were trapped first at the level of interdigitated microelectrodes with the help of dielectrophoresis. Correlation of the cells dielectric characteristics that was obtained via electrical impedance spectroscopy (EIS) allowed evident differentiation of the various types of cell. The differentiations were assigned to a “dielectric phenotype” based on their crossover frequencies. Finally, Randles equivalent circuit model was employed for highlighting the differences with regard to a series group of charge transport resistance and constant phase element for cancerous and normal cells.
“…The CPE element is explained in terms of a fractional parameter α and a parameter P = ηC , in which η is a calibration function, where R , C , P, and α are adjustable parameters. Α takes a value of + 1 or − 1 for a capacitive or inductive reactive impedance, respectively, and determines the meaning of P 36 . Figure 10 Equivalent circuit for ( a ) HYD-T and ( b ) CAN-T hybrid materials; schematic processes in the ( c ) HYD-T and ( d ) CAN-T hybrid materials.…”
Section: Resultsmentioning
confidence: 99%
“…Fitted parameters between light and dark conditions exhibit differences expressed as percentages, registered in Table 2 . The difference was calculated according to the equation 36 : …”
Degradation of pollutants in aqueous medium is of high interest due to the impact on environment and human health, therefore, design and study of the physico-chemical properties of photocatalysts for water remediation are of major significance. Among properties of photocatalyst, those related to the surface and electrical mechanism are crucial to the photocatalyst´s performance. Here we report the chemical and morphological characteristics of TiO2@zeolite photocatalyst by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) respectively, and a coherent electrical conduction mechanism was proposed based on data obtained from assisted laser impedance spectroscopy (ALIS), in which the zeolite was synthesized from recycled coal fly ash. The results obtained by SEM and XPS verified the presence of spherical particles of TiO2 anatase with presence of Ti3+ state. ALIS results showed that impedance of the entire system increases when the amount of TiO2 increases and the samples with lower capacitive performance allowed a larger transfer of the charges between the solid–liquid interface. All results showed that higher photocatalytic performance of TiO2 growth over hydroxysodalite with 8.7 wt% and 25 wt% of TiO2 can be explained in terms of the morphology of TiO2 and the interactions between substrate-TiO2 mainly.
“…Among these methods, DS is a non-invasive, fast, and promising method for cell screening. DS has been widely used for impedance measurements of yeast cells [10][11][12], breast cancer cells [13], lymphocyte activation profiling [14], monitoring performance of epithelial tissues [15], and hepatology research [16].…”
Dielectric spectroscopy (DS) is a promising cell screening method that can be used for diagnostic and drug discovery purposes. The primary challenge of using DS in physiological buffers is the electrode polarization (EP) that overwhelms the impedance signal within a large frequency range. These effects further amplify with the miniaturization of the measurement electrodes. In this study, we present a microfluidic system and the associated equivalent circuit models for real-time measurements of cell membrane capacitance and cytoplasm resistance in physiological buffers with 10 s increments. The current device captures several hundreds of biological cells in individual microwells through gravitational settling and measures the system’s impedance using microelectrodes covered with dendritic gold nanostructures. Using PC-3 cells (a highly metastatic prostate cancer cell line) suspended in cell growth media (CGM), we demonstrate stable measurements of cell membrane capacitance and cytoplasm resistance in the device for over 15 min. We also describe a consistent application of the equivalent circuit model, starting from the reference measurements used to determine the system parameters. The circuit model is tested using devices with varying dimensions, and the obtained cell parameters between different devices are nearly identical. Further analyses of the impedance data have shown that accurate cell membrane capacitance and cytoplasm resistance can be extracted using a limited number of measurements in the 5 MHz to 10 MHz range. This will potentially reduce the timescale required for real-time DS measurements below 1 s. Overall, the new microfluidic device can be used for the dielectric characterization of biological cells in physiological buffers for various cell screening applications.
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