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Continuous differential impedance spectroscopy of single cells.

Malleo D, Nevill JT, Lee LP, Morgan H - Microfluid Nanofluidics (2009)

Bottom Line: Measurements are accomplished by recording the current from two closely-situated electrode pairs, one empty (reference) and one containing a cell.We demonstrate time-dependent measurement of single cell impedance produced in response to dynamic chemical perturbations.ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-009-0534-2) contains supplementary material, which is available to authorized users.

View Article: PubMed Central - PubMed

ABSTRACT
A device for continuous differential impedance analysis of single cells held by a hydrodynamic cell trapping is presented. Measurements are accomplished by recording the current from two closely-situated electrode pairs, one empty (reference) and one containing a cell. We demonstrate time-dependent measurement of single cell impedance produced in response to dynamic chemical perturbations. First, the system is used to assay the response of HeLa cells to the effects of the surfactant Tween, which reduces the impedance of the trapped cells in a concentration dependent way and is interpreted as gradual lysis of the cell membrane. Second, the effects of the bacterial pore-forming toxin, Streptolysin-O are measured: a transient exponential decay in the impedance is recorded as the cell membrane becomes increasingly permeable. The decay time constant is inversely proportional to toxin concentration (482, 150, and 30 s for 0.1, 1, and 10 kU/ml, respectively). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-009-0534-2) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Data showing the effect of SLO on the impedance spectrum from single cells. Three different concentrations were assayed and differential impedance spectra were acquired over time. The data represented here was sampled at the frequency of 300 kHz. The exponential curves (solid lines) are the average responses for 10, 1, 100 U/ml. We postulate that the effect of the osmotic swelling evident for the 100 U/ml and 1 kU/ml is swamped by the effect of the membrane poration that occurs at a much faster rate with 10 kU/ml. However, it is difficult to confirm this conclusion unequivocally by means of impedance spectroscopy because the swelling causes an increase in impedance, whereas poration of the membrane causes a decrease, two contrasting effects that mask each other
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Fig6: Data showing the effect of SLO on the impedance spectrum from single cells. Three different concentrations were assayed and differential impedance spectra were acquired over time. The data represented here was sampled at the frequency of 300 kHz. The exponential curves (solid lines) are the average responses for 10, 1, 100 U/ml. We postulate that the effect of the osmotic swelling evident for the 100 U/ml and 1 kU/ml is swamped by the effect of the membrane poration that occurs at a much faster rate with 10 kU/ml. However, it is difficult to confirm this conclusion unequivocally by means of impedance spectroscopy because the swelling causes an increase in impedance, whereas poration of the membrane causes a decrease, two contrasting effects that mask each other

Mentions: When cells were perfused with DTT-activated SLO (in PBS) a similar change in impedance magnitude was recorded (Fig. 6). A solution of 100 U/ml caused an initial increase in impedance (cell swelling) followed by a gradual decrease; 1 kU/ml had a similar but more pronounced effect. The decreases were fitted by a single exponential decay with characteristic times shown in Table 1. Higher concentrations of toxin caused faster decays, but the final value of impedance is the same for each case as the cell is porated and becomes electrically transparent. This data indicate that the final value of the impedance magnitude is independent of toxin concentration in the solution. Unlike the data for Tween, where the cells appear to be completely lysed, the change in impedance is not as great. The rate of change of impedance and, therefore, the rate of pore insertion were significantly faster for the higher concentration solution (10 kU/ml in 20 s). From simulation, the magnitude of the change in impedance can be correlated with a change in membrane conductance (assuming no other parameters change). Based on our model, the recorded value of a 10% change in impedance magnitude at 300 kHz is equivalent to the insertion of ~10,000 pores.Fig. 6


Continuous differential impedance spectroscopy of single cells.

Malleo D, Nevill JT, Lee LP, Morgan H - Microfluid Nanofluidics (2009)

Data showing the effect of SLO on the impedance spectrum from single cells. Three different concentrations were assayed and differential impedance spectra were acquired over time. The data represented here was sampled at the frequency of 300 kHz. The exponential curves (solid lines) are the average responses for 10, 1, 100 U/ml. We postulate that the effect of the osmotic swelling evident for the 100 U/ml and 1 kU/ml is swamped by the effect of the membrane poration that occurs at a much faster rate with 10 kU/ml. However, it is difficult to confirm this conclusion unequivocally by means of impedance spectroscopy because the swelling causes an increase in impedance, whereas poration of the membrane causes a decrease, two contrasting effects that mask each other
© Copyright Policy
Related In: Results  -  Collection

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Fig6: Data showing the effect of SLO on the impedance spectrum from single cells. Three different concentrations were assayed and differential impedance spectra were acquired over time. The data represented here was sampled at the frequency of 300 kHz. The exponential curves (solid lines) are the average responses for 10, 1, 100 U/ml. We postulate that the effect of the osmotic swelling evident for the 100 U/ml and 1 kU/ml is swamped by the effect of the membrane poration that occurs at a much faster rate with 10 kU/ml. However, it is difficult to confirm this conclusion unequivocally by means of impedance spectroscopy because the swelling causes an increase in impedance, whereas poration of the membrane causes a decrease, two contrasting effects that mask each other
Mentions: When cells were perfused with DTT-activated SLO (in PBS) a similar change in impedance magnitude was recorded (Fig. 6). A solution of 100 U/ml caused an initial increase in impedance (cell swelling) followed by a gradual decrease; 1 kU/ml had a similar but more pronounced effect. The decreases were fitted by a single exponential decay with characteristic times shown in Table 1. Higher concentrations of toxin caused faster decays, but the final value of impedance is the same for each case as the cell is porated and becomes electrically transparent. This data indicate that the final value of the impedance magnitude is independent of toxin concentration in the solution. Unlike the data for Tween, where the cells appear to be completely lysed, the change in impedance is not as great. The rate of change of impedance and, therefore, the rate of pore insertion were significantly faster for the higher concentration solution (10 kU/ml in 20 s). From simulation, the magnitude of the change in impedance can be correlated with a change in membrane conductance (assuming no other parameters change). Based on our model, the recorded value of a 10% change in impedance magnitude at 300 kHz is equivalent to the insertion of ~10,000 pores.Fig. 6

Bottom Line: Measurements are accomplished by recording the current from two closely-situated electrode pairs, one empty (reference) and one containing a cell.We demonstrate time-dependent measurement of single cell impedance produced in response to dynamic chemical perturbations.ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-009-0534-2) contains supplementary material, which is available to authorized users.

View Article: PubMed Central - PubMed

ABSTRACT
A device for continuous differential impedance analysis of single cells held by a hydrodynamic cell trapping is presented. Measurements are accomplished by recording the current from two closely-situated electrode pairs, one empty (reference) and one containing a cell. We demonstrate time-dependent measurement of single cell impedance produced in response to dynamic chemical perturbations. First, the system is used to assay the response of HeLa cells to the effects of the surfactant Tween, which reduces the impedance of the trapped cells in a concentration dependent way and is interpreted as gradual lysis of the cell membrane. Second, the effects of the bacterial pore-forming toxin, Streptolysin-O are measured: a transient exponential decay in the impedance is recorded as the cell membrane becomes increasingly permeable. The decay time constant is inversely proportional to toxin concentration (482, 150, and 30 s for 0.1, 1, and 10 kU/ml, respectively). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10404-009-0534-2) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus