Specific membrane capacitance, cytoplasm conductivity and instantaneous Young's modulus of single tumour cells

As label-free biomarkers, biophysical properties of cells are widely used for cell type classification. However, intrinsic biophysical markers, e.g., specific membrane capacitance (C_{specific membrane}), cytoplasm conductivity (σ_conductivity) and instantaneous Young's modulus (E_{instantaneous}) measured for hundreds of single cells were not yet reported. In this study, single cells in suspension (adherent cells treated with trypsin) were aspirated through a microfluidic constriction channel at 25 °C, and the entry processes and impedance profiles were recorded and translated to C_{specific membrane}, σ_conductivity and E_{instantaneous}. C_{specific membrane}, σ_conductivity and E_{instantaneous} of five cell types were quantified as 2.10±0.38 μF cm^-2, 0.91±0.15 S m^-1 and 5.52±0.95 kPa for H460 cells (n_cell=437); 2.52±0.54 μF cm^-2, 0.83±0.12 S m^-1 and 5.54±1.04 kPa for H446 cells (n_cell=410); 2.45±0.57 μF cm^-2, 0.99±0.18 S m^-1 and 5.16±1.68 kPa for A549 cells (n_cell=442); 1.86±0.31 μF cm^-2, 1.07±0.18 S m^-1 and 3.86±0.81 kPa for 95D cells (n_cell=415); 2.03±0.35 μF cm^-2, 0.99±0.16 S m^-1 and 3.49±0.70 kPa for 95C cells (n_cell=290). The database of C_{specific membrane}, σ_conductivity and E_{instantaneous} may serve as a reference for future studies of cellular biophysical properties.