Single-cell impedance spectroscopy of nucleated cells†

Single-cell microfluidic impedance spectroscopy is widely used to characterise single cells, but the intrinsic electrical properties are rarely determined owing to the limited number of data points across a wide frequency bandwidth. To address this shortcoming, we have developed a system with an extended frequency range (to 550 MHz) that measures the impedance spectrum of single nucleated cells at high throughput. The system was evaluated using HL60 cells treated with glutaraldehyde or cytochalasin D, and THP-1 cells differentiated into macrophages. The impedance data was fitted to the double-shell model to obtain cell membrane capacitance and cytoplasm conductivity. It is shown that reducing the conductivity of the suspension media significantly enhances the dielectric relaxations of the cell membrane, allowing small differences between control and chemically modified cells to be discriminated.