Biological Compatibility of Electromanipulation Media

Abstract

Electromanipulation of cells, which includes dielectrophoresis, electrorotation, and electrophoresis, as a label free cell manipulation and characterization tool has gained particular interest recently. However, the applicability of electromanipulation to biological cells is limited to cells suspended in special types of media containing lower amounts of salts in comparison to physiological buffers. Impedance measurements of cells are often performed in low conductive buffers, mainly due to parasitic capacitance that occurs at the electrode electrolyte interface. One might question the use of electromanipulation buffers as it results in lower transmembrane transport and possible increased cellular death. Therefore, in this study, effects of electromanipulation buffers with varying salt concentrations on cellular viability and transmembrane transport was studied for a human T-cell leukemia cell line (Jurkat). Cellular viability was measured in vitro using an MTT cell viability assay. Cellular death was also measured using the trypan blue dye exclusion method. Membrane capacitance and conductance was measured by impedance spectroscopy over a range of extracellular salt concentrations. We described the cell membrane conductance at different extracellular salt concentrations using a quantitative model. Even though membrane conductance measurements by impedance spectroscopy is indicative of number and activity of ion channels even performed at low extracellular salt levels; results indicate that cells in electromanipulation buffers have reduced viability. Strategies to increase metabolic activity by changing buffer composition while still retaining the performance of impedance spectroscopy and electromanipulation are also presented.