Controlling cell destruction using dielectrophoretic forces

Abstract

Measurements are reported of the main factors, namely the AC voltage frequency and magnitude, that were observed to influence the number of cells destroyed during dielectrophoresis (DEP) experiments on Jurkat T cells and HL60 leukemia cells. Microelectrodes of interdigitated and quadrupolar geometries were used. A field-frequency window has been identified that should be either avoided or utilised, depending on whether or not cell damage is to be minimised or is a desired objective. The width and location of this frequency window depends on the cell type, as defined by cell size, morphology and dielectric properties, and is bounded by two characteristic frequencies. These frequencies are the DEP cross-over frequency, where a cell makes the transition from negative to positive DEP, and a frequency determined by the time constant that controls the frequency dependence of the field induced across the cell membrane. When operating in this frequency window, and for the microelectrode designs used in this work, cell destruction can be minimised by ensuring that cells are not directed by positive DEP to electrode edges where fields exceeding 30-40 kV/m are generated. Alternatively, this field-frequency window can be exploited to selectively destroy specific cell types in a cell mixture.

Electrokinetic measurements of membrane capacitance and conductance for pancreatic -cells

“…This effect was partially overcome by applying an ER signal to the electrodes during the initial loading of the islet cells. However, a better approach will be to chemically treat or coat the glass substrate to reduce cell adhesion, and this is currently being experience much larger DEP forces and field stresses than cells further away from the electrodes, and this is a particularly relevant consideration when operating at a field frequency close to the DEP cross-over frequency f xo [21]. This, in turn, could lead to an increased passive conduction of ions through membrane pores and to increased conduction of ions over the cell membrane surface.…”

An electrostatic microwell–based biochip for phytoplanktonic cell trapping

“…Similarly to trapping cells with an electric field using a micropatterned electrode, electrical charge may affect the cells. 17,18 It may also be of a concern that preventing cells to be naturally free-floating eventually results in changed growth kinetics. To study the effect of the charged surface on growth kinetics, we monitored groups of S. platensis filaments grown under 3 different conditions (10 groups each, mean 6 SD of initial filament number ¼ 9.8 6 1.4): (1) in wells with the positively charged based, (2) in wells with normal glass surface base, and (3) in static bulk culture (500 ml flask).…”

“…The electrical field may also affect cell proliferation. 17,18 Cell trapping based on suction, 15,19 channel constriction 20 or microcage 21 may be considered a less costly alternative. Their great difficulty is that there is not a single universal trap design of this kind that can handle multiple types of algal species.…”

Creation of arrays of cell aggregates in defined patterns for developmental biology studies using dielectrophoresis

“…The optimum conditions for obtaining positive dielectrophoresis of cells are relatively constant for different cell types (1 MHz; medium conductivity as low as possible to maximize the DEP force), and the electric field strength that could be used was determined by ability of the cell to maintain its viability (Menachery and Pethig, 2005). Therefore, the major factor that could be optimized was the flow rate.…”