Microfluidic Cytometry for High‐Throughput Characterization of Single Cell Cytoplasmic Viscosity Using Crossing Constriction Channels

Abstract

This article presents an approach of microfluidic flow cytometry capable of continuously characterizing cytoplasmic viscosities of single cells. The microfluidic system consists of a major constriction channel and a side constriction channel perpendicularly crossing each other. Cells are forced to rapidly travel through the major channel and are partially aspirated into the side channel when passing the channel junction. Numerical simulations were conducted to model the time dependence of the aspiration length into the side channel, which enables the measurement of cytoplasmic viscosity by fitting the model results to experimental data. As a demonstration for high‐throughput measurement, the cytoplasmic viscosities of HL‐60 cells that were native or treated by N‐Formylmethionine‐leucyl‐phenylalanine (fMLP) were quantified with sample sizes as large as thousands of cells. Both the average and median cytoplasmic viscosities of native HL‐60 cells were found to be about 10% smaller than those of fMLP‐treated HL‐60 cells, consistent with previous observations that fMLP treatment can increase the rigidity of white blood cells. Furthermore, the microfluidic system was used to process granulocytes from three donors (sample size >1,000 cells for each donor). The results revealed that the cytoplasmic viscosity of granulocytes from one donor was significantly higher than the other two, which may result from the fact that this donor just recovered from an inflammation. In summary, the developed microfluidic system can collect cytoplasmic viscosities from thousands of cells and may function as an enabling tool in the field of single‐cell analysis. © 2019 International Society for Advancement of Cytometry

Microfluidic Systems for Blood and Blood Cell Characterization

“…Wang et al [184] and Liu et al [180] developed a microfluidic platform to characterize the cytoplasmic viscosity (µ cy ), cytoplasmic conductivity (σ cy ), and specific membrane capacitance (C sm ) of single cells (Figure 10D). Before invading the lateral narrowed channels, the moving cell was pushed through the main microfluidic constriction channel.…”

Performance-enhanced clogging-free viscous sheath constriction impedance flow cytometry

“…Therefore, as a label-free technique, impedance flow cytometry (IFC) has emerged for single cell analysis through electrophysiology. [12][13][14][15][16][17][18] So far, IFC techniques have made progress in high-content measurement of single-cell biophysical multi-modal fingerprints including cell size, 19 shape, 20 and electrical [21][22][23] and mechanical properties. 24,25 Most of the IFC techniques use a narrow channel [26][27][28][29][30][31][32][33] as mechanical constriction (MC) to decrease the sensing aperture (SA), which matches the cell size to achieve high detection sensitivity.…”

“…Therefore, as a label-free technique, impedance flow cytometry (IFC) has emerged for single cell analysis through electrophysiology. 12–18 So far, IFC techniques have made progress in high-content measurement of single-cell biophysical multi-modal fingerprints including cell size, 19 shape, 20 and electrical 21–23 and mechanical properties. 24,25…”

Advance of microfluidic constriction channel system of measuring single‐cell cortical tension/specific capacitance of membrane and conductivity of cytoplasm

“…For the sake of detection of single-cell mechanical properties, individual cells travel through and deform in the microfluidic channels with transit time or deformations captured due to fluid stresses and/or geometrical constrictions [30][31][32][33][34]. Using corresponding biomechanical models, these preliminary data of cell deformations or transit time were translated into inherent biomechanical properties of single cells including elastic modulus and cortical tension [35][36][37][38][39][40][41].…”