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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

a Overview of the experimental setup. The microfluidic device is mounted on a PCB board, which makes electrical connections to the chip and interfaces to a computer and the impedance analyzer. A microscope is used to image the device, and a syringe pump to flow cells and media. b Image of a device with tubing attached via PDMS ports, scale bar = 1 cm. c Photograph of the channel containing multiple trapping sites, each of which has a pair of electrodes/traps, scale bar = 250 μm. d Schematic cross section of the trapping region showing the two electrodes used for differential measurements. e Image of traps with 15 μm beads captured in traps above master electrodes. Note that the reference traps are empty, because they face downstream. f Image of a trapped single HeLa cell, labeled with Celltracker™, scale bar = 30 μm
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Fig1: a Overview of the experimental setup. The microfluidic device is mounted on a PCB board, which makes electrical connections to the chip and interfaces to a computer and the impedance analyzer. A microscope is used to image the device, and a syringe pump to flow cells and media. b Image of a device with tubing attached via PDMS ports, scale bar = 1 cm. c Photograph of the channel containing multiple trapping sites, each of which has a pair of electrodes/traps, scale bar = 250 μm. d Schematic cross section of the trapping region showing the two electrodes used for differential measurements. e Image of traps with 15 μm beads captured in traps above master electrodes. Note that the reference traps are empty, because they face downstream. f Image of a trapped single HeLa cell, labeled with Celltracker™, scale bar = 30 μm

Mentions: A number of published methods (Cho and Thielecke 2007; Han and Frazier 2006; James et al. 2008; Han et al. 2007; Jang and Wang 2007) describe single cell capture coupled with impedance analysis. So far, no device features a differential electrode arrangement that measures multiple signals from multiple trapping sites. We have developed such a system, and the design and operation are shown in Fig. 1. The device sits on a microscope stage and is connected to an impedance analyzer. Syringe pumps are used to inject cells and perfuse medium and/or drugs into the chip. Individually addressable electrodes and micrometer-sized traps are integrated in a microfluidic platform. Single cells are hydrodynamically trapped; measurements are performed by normalizing the spectrum of a trap containing a single cell to a counterpart empty trap. Long-term studies are, therefore, not influenced by local changes in temperature, pH, or conductivity. The recorded spectrum is analyzed to quantify changes in the electrical parameters of an individual cell’s membrane.Fig. 1


Continuous differential impedance spectroscopy of single cells.

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

a Overview of the experimental setup. The microfluidic device is mounted on a PCB board, which makes electrical connections to the chip and interfaces to a computer and the impedance analyzer. A microscope is used to image the device, and a syringe pump to flow cells and media. b Image of a device with tubing attached via PDMS ports, scale bar = 1 cm. c Photograph of the channel containing multiple trapping sites, each of which has a pair of electrodes/traps, scale bar = 250 μm. d Schematic cross section of the trapping region showing the two electrodes used for differential measurements. e Image of traps with 15 μm beads captured in traps above master electrodes. Note that the reference traps are empty, because they face downstream. f Image of a trapped single HeLa cell, labeled with Celltracker™, scale bar = 30 μm
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2944380&req=5

Fig1: a Overview of the experimental setup. The microfluidic device is mounted on a PCB board, which makes electrical connections to the chip and interfaces to a computer and the impedance analyzer. A microscope is used to image the device, and a syringe pump to flow cells and media. b Image of a device with tubing attached via PDMS ports, scale bar = 1 cm. c Photograph of the channel containing multiple trapping sites, each of which has a pair of electrodes/traps, scale bar = 250 μm. d Schematic cross section of the trapping region showing the two electrodes used for differential measurements. e Image of traps with 15 μm beads captured in traps above master electrodes. Note that the reference traps are empty, because they face downstream. f Image of a trapped single HeLa cell, labeled with Celltracker™, scale bar = 30 μm
Mentions: A number of published methods (Cho and Thielecke 2007; Han and Frazier 2006; James et al. 2008; Han et al. 2007; Jang and Wang 2007) describe single cell capture coupled with impedance analysis. So far, no device features a differential electrode arrangement that measures multiple signals from multiple trapping sites. We have developed such a system, and the design and operation are shown in Fig. 1. The device sits on a microscope stage and is connected to an impedance analyzer. Syringe pumps are used to inject cells and perfuse medium and/or drugs into the chip. Individually addressable electrodes and micrometer-sized traps are integrated in a microfluidic platform. Single cells are hydrodynamically trapped; measurements are performed by normalizing the spectrum of a trap containing a single cell to a counterpart empty trap. Long-term studies are, therefore, not influenced by local changes in temperature, pH, or conductivity. The recorded spectrum is analyzed to quantify changes in the electrical parameters of an individual cell’s membrane.Fig. 1

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