Using Impedance Flow Cytometry for Rapid Viability Classification of Heat-Treated Bacteria

Abstract

In the future, rapid electrical characterization of cells with impedance flow cytometry promises to be a fast and accurate method for the evaluation of cell properties. In this paper, we investigate how the conductivity of the suspending medium along with the heat exposure time affects the viability classification of heat-treated E. coli. Using a theoretical model, we show that perforation of the bacteria membrane during heat exposure changes the impedance of the bacterial cell from effectively less conducting than the suspension medium to effectively more conducting. Consequently, this results in a shift in the differential argument of the complex electrical current that can be measured with impedance flow cytometry. We observe this shift experimentally through measurements on E. coli samples with varying medium conductivity and heat exposure times. We show that increased exposure time and lower medium conductivity results in improved classification between untreated and heat-treated bacteria. The best classification was achieved with a medium conductivity of 0.045 S/m after 30 min of heat exposure.

Strategic regulation of barrier characteristics of biofilms to enhance the extracellular electrogenic performance in MFCs: an electrochemical dynamic evaluation study

“…This evidences the fact that bacterial cells themselves consist of redox active groups which effectively decrease the migration resistance of free charges and promote electron transfer via electron hopping. 61 These results are in contrast to previous reports that the biolm is a decisive variable for MFC performance. 62 The barrier characteristics of the Gram-positive bacterial biolm are further comprehensively evaluated.…”

“…Sporulating or lysing cells are less conductive and affect the overall cell performance. 61 The comparative validation of the Z r value with cell viability is shown in Fig. 4E.…”

Rapid Screening of Urinary Tract Infection Using Microfluidic Inertial-Impedance Cytometry

“…Heterogeneity of urine characteristics can adversely influence single-cell impedance measurement as the technique is based on the quantification of impedance contrast of cells/ particles and their surrounding conductive medium between a pair of electrodes. 18 Figure S1 highlights this issue as impedance profiling of neutrophils and Human bladder carcinoma cell line (HTB-9) in different mediums (PBS and urine) showed different measured cell characteristics in terms of differential impedance magnitudes between two cell populations. We next examined the platform's capability to perform buffer exchange by using Fluorescein isothiocyanate (FITC) in PBS as a sample to represent the aqueous phase in urine.…”

On the compatibility of single-cell microcarriers (nanovials) with microfluidic impedance cytometry

“…[1][2][3] By means of multifrequency electrical impedance measurements, MIC measures the electrical phenotype of individual biological cells, which is related to cell type and status. MIC has been extensively used for the label-free characterization of mammalian cells, human pathogens, and plant cells, for applications including viability assessment, [4][5][6] subpopulation distinction, [7][8][9][10] antimicrobial susceptibility testing [11][12][13][14] and deformability assessment. 15,16 MIC has also been reported as a tool for the non-invasive monitoring of 3D cell cultures under continuous flow, 17,18 and impedance-based microfluidic sorters have been proposed for sorting cells upon their electrical phenotype.…”