"Flow cytometry is a valuable tool for the simultaneous assessment of necrosis and apoptosis in a single population of cells. Necrosis is detected by measuring the permeability of the plasma membrane to a normally impermeable fluorescent dye, such as the DNA-binding dye propidium iodide (PI)."
We present the first use of amperometric detection to assess the viability of mammalian cells in continuous mode, directly in the cell culture medium. Vero or HeLa cells were injected into electrochemical sensors equipped with a 3-electrode system and containing DCIP 50 µM used as the redox mediator. DCIP was reduced by the viable cells and the reduced form was detected amperometrically at 300 mV vs silver pseudo-reference. The continuous regeneration of the oxidized form of the mediator ensured a stable redox state of the cell environment, allowing the cells to survive during the measurement time. The electrochemical response was related to cell metabolism (no response with dead cells or lysed cells) and depended on both mediator concentration and cell density. The protocol was applied to both cells in suspension and adhered cells. It was also adapted to detect trans-plasma membrane electron transfer (tPMET) by replacing DCIP by ferricyanide 500 µM and using linear scan voltammetry (2 mV/s). The pioneering results described here pave the way to the development of routine electrochemical assays for cell viability and for designing a cell-based analytical platform.]
[Highlights
Viability of mammalian cells was assessed by amperometric detection.
A redox mediator is reduced by the cells and re-oxidized on the polarised electrode.
No current was detected with dead cells or solutions resulting from cell lysis.
The assay works with both suspended cells and cells adhered on the electrode surface.
tPMET can be detected by using ferricyanide instead of DCIP as redox mediator.]