Dielectrophoretic field-flow fractionation system for detection of aquatic toxicants.

Dielectrophoretic field-flow fractionation (dFFF) was applied as a contact-free way to sense changes in the plasma membrane capacitances and conductivities of cultured human HL-60 cells in response to toxicant exposure. A micropatterned electrode imposed electric forces on cells in suspension in a parabolic flow profile as they moved through a thin chamber. Relative changes in the dFFF peak elution time, reflecting changes in cell membrane area and ion permeability, were measured as indices of response during the first 150 min of exposure to eight toxicants having different single or mixed modes of action (acrylonitrile, actinomycin D, carbon tetrachloride, endosulfan, N-nitroso- N-methylurea (NMU), paraquat dichloride, puromycin, and styrene oxide). The dFFF method was compared with the cell viability assay for all toxicants and with the mitochondrial potentiometric dye assay or DNA alkaline comet assay according to the mode of action of the specific agents. Except for low doses of nucleic acid-targeting agents (actinomycin D and NMU), the dFFF method detected all toxicants more sensitively than other assays, in some cases up to 10 (5) times more sensitively than the viability approach. The results suggest the dFFF method merits additional study for possible applicability in toxicology.