Passive electrical properties of RBC suspensions: changes due to distribution of relaxation times in dependence on the cell volume fraction and medium conductivity

Fomekong, Robert D.; Pliquett, Uwe; Pliquett, F

doi:10.1016/s0302-4598(98)00161-5

Cited by 19 publications

(8 citation statements)

References 13 publications

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“…It must be noted that there are some previous works that indicate that deviations from the Cole model are related somehow to cell aggregation or clusterization. For instance, it has been shown that α decreases when blood hematocrit increases (Fomekong et al 1998) or that dispersion broadening occurs during embryogenesis (Asami and Irimajiri 2000). In this sense, the present paper can be considered a reinforcement of that interpretation.…”

Section: Introductionmentioning

confidence: 53%

Bioimpedance dispersion width as a parameter to monitor living tissues

et al. 2005

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In the case of living tissues, the spectral width of the electrical bioimpedance dispersions (closely related with the alpha parameter in the Cole equation) evolves during the ischemic periods. This parameter is often ignored in favor of other bioimpedance parameters such as the central frequency or the resistivity at low frequencies. The object of this paper is to analyze the significance of this parameter through computer simulations (in the alpha and beta dispersion regions) and to demonstrate its practical importance through experimental studies performed in rat kidneys during cold preservation. The simulations indicate that the dispersion width could be determined by the morphology of the extra-cellular spaces. The experimental studies show that it is a unique parameter able to detect certain conditions such as a warm ischemia period prior to cold preservation or the effect of a drug (Swinholide A) able to disrupt the cytoskeleton. The main conclusion is that, thanks to the alpha parameter in the Cole equation, the bioimpedance is not only useful to monitor the intra/extra-cellular volume imbalances or the inter-cellular junctions resistance but also to detect tissue structural alterations.

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Section: Introductionmentioning

confidence: 53%

Bioimpedance dispersion width as a parameter to monitor living tissues

et al. 2005

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“…The membrane of the cell is essentially non-conducting and is represented by a capacitance c m , which ranges between 0.7 to 2.5 mF cm 22 for biological cells. [30][31][32][33][34][35] The simple single shell model from Pauly and Schwan results essentially in a dispersion of the Debye type, which is defined by the following set of equations: 16,36 (4)…”

Section: Dispersion Theory and Impedance Spectrum Of A Single Cell Su...mentioning

confidence: 99%

Dielectric spectroscopy in a micromachined flow cytometer: theoretical and practical considerations

et al. 2004

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We propose a model to determine the influence of different cell properties, such as size, membrane capacitance and cytoplasm conductivity, on the impedance spectrum as measured in a microfabricated cytometer. A dielectric sphere of equivalent complex permittivity is used as a simplified model to describe a biological cell. The measurement takes place between a pair of facing microelectrodes in a microchannel filled with a saline solution. The model incorporates various cell parameters, such as dielectric properties, size and position in the channel. A 3D finite element model is used to evaluate the magnitude of the electric field in the channel and the resultant changes in charge densities at the measurement electrode boundaries as a cell flows past. The charge density is integrated on the electrode surface to determine the displacement current and the channel impedance for the computed frequency range. The complete impedance model combines the finite element model, the electrode-electrolyte interface impedance and stray impedance, which are measured from a real device. The modeled dielectric complex spectra for various cell parameters are discussed and a measurement strategy for cell discrimination with such a system is proposed. We finally discuss the amount of noise and measurement fluctuations of the sensor.

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“…Relatively high E a,dc values for the buffered systems (containing large number of ions) can be caused by much higher activation energy of the motion of citrate anions than that of protons and the trapping effects of anions (and glucose molecules) for protons. Notice that the intracellular conductivity in RBCs is 0.5 − 0.8 S/m [29], and the RBC cytoplasm is not an ideal suspension, since the conductivity for the given ionic strength should be as twice as high, i.e., about 1.2 − 1.4 S/m [29] than can be explained by the interactions of ions with the large haemoglobin and other macromolecules, which decrease the mobility of ions. The effects of silica on the E a,dc value is due to changes in the structure of the hydrogen bond network in the interfacial water, induced conformation changes in biomacromolecules and RBCs, and an increase in concentration of mobile protons on dissociation of silanols.…”

Section: Resultsmentioning

confidence: 99%

“…In the case of water/organics mixtures, polar and charged organic molecules can contribute the TSDC spectra [24]. Notice that different electrophysical methods are frequently used to study RBCs [26][27][28][29].…”

Section: Tablementioning

confidence: 99%

Interaction of unmodified and partially silylated nanosilica with red blood cells

et al. 2007

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Abstract:Interaction of red blood cells (RBCs) with unmodified and partially (50%) silylated fumed silica A-300 (nanosilica) was studied by microscopic, XRD and thermally stimulated depolarisation current (TSDC) methods. Nanosilica at a low concentration C A−300 < 0.01 wt.% in buffered aqueous suspension is characterised by a weak haemolytic effect on RBCs. However, at C A−300 = 1 wt% all RBCs transform into shadow corpuscles because of 100% haemolysis. Partial (one-half) hydrophobization of nanosilica leads to reduction of the haemolytic effect in comparison with unmodified silica at the same concentrations. A certain portion of the TSDC spectra of the buffered suspensions with RBC/A-300 is independent of the amounts of silica. However, significant portions of the low-and high-temperature TSDC bands have a lower intensity at C A−300 = 1 wt% than that for RBCs alone or RBC/A-300 at C A−300 = 0.01 wt.% because of structural changes in RBCs. Results of microscopic and XRD investigations and calculations using the TSDC-and NMR-cryoporometry suggest that the intracellular structures in RBCs (both organic and aqueous components) depend on nanosilica concentration in the suspension.

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Passive electrical properties of RBC suspensions: changes due to distribution of relaxation times in dependence on the cell volume fraction and medium conductivity

Cited by 19 publications

References 13 publications

Bioimpedance dispersion width as a parameter to monitor living tissues

Bioimpedance dispersion width as a parameter to monitor living tissues

Dielectric spectroscopy in a micromachined flow cytometer: theoretical and practical considerations

Interaction of unmodified and partially silylated nanosilica with red blood cells

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