Modifying dielectrophoretic response of nonviable yeast cells by ionic surfactant treatment.

Nonviable cells are essential biosystems, due to the functionalities they offer and their effects on viable cells. Therefore, the separation and immobilization of nonviable cells separately or in the vicinity of viable cells is of great importance for many fundamentals investigations in cell biology. However, most nonviable cells become less polarizable than the surrounding medium at conductivities above 0.01 S/m. This means that in such a medium, dielectrophoresis, despite its great versatilities for manipulation of cells, cannot be employed for immobilizing nonviable cells. Here, we present a novel approach to change the dielectrophoretic (DEP) response of nonviable yeast cells by treating them with low concentrations of ionic surfactants such as sodium dodecyl sulfate. After this treatment, they exhibit a strong positive DEP response, even at high medium conductivities. The capability of this treatment is demonstrated in two proof-of-concept experiments. First, we show the sorting and immobilization of viable and nonviable yeast cells, along consecutive microelectrode arrays. Second, we demonstrate the immobilization of viable and nonviable cells in the vicinity of each other along the same microelectrode array. The proposed technique allows DEP platforms to be utilized for the immobilization and subsequent postanalysis of both viable and nonviable cells with and without the presence of each other.