Dielectrophoresis and ζ-potential as potential low-cost complements to patch clamp for measurement of cell electrophysiology

Cell electrophysiology is a useful measure of cell function, including ionic state and channel activity, and the way these are altered by pharmacological intervention. However, measurement of whole-cell electrical properties such as resting membrane potential Vm and membrane whole-cell capacitance and conductance is difficult, which has limited the more widespread adoption of electrophysiology in cell biology and drug discovery. The gold-standard method for acquiring this data is patch clamp, a method of measuring single cells that uses a micromanipulated micropipette in contact with the cell surface. Measurement is difficult, slow, and requires a highly skilled operator, whilst automated alternatives are expensive to run. Other methods such as flow cytometry are unable to provide absolute values of Vm, or measure conductance and capacitance characteristics. Dielectrophoresis (DEP) and electrophoretic light scattering (ELS) have recently been shown to provide useful methods of directly measuring absolute Vm and other parameters, whilst examining many more cells (typically tens of thousands in under a minute). In this paper we use DEP and ELS to examine the electrophysiology of human bladder carcinoma cell line HTB-9 following treatment with ATP, glibenclamide and tetraethylammonium, and compare the results to published data obtained by patch clamp. Results indicate that DEP yields Vm and membrane conductance values that are highly comparable to data from patch clamp, at high speed and low cost, demonstrating the usefulness of techniques such as DEP and ELS for electrophysiological study.