Development of a microfabricated device for low-voltage electropermeabilization of adherent cells.

A microfabricated device for low-voltage electropermeabilization of adherent cells has been developed. The device, which is fabricated on a cover glass using mainly transparent materials, allows optical observation of cells through it. This device consists of an array of 6-μm circular electrodes connected via a transparent and conductive layer made of ITO (indium tin oxide) to give pulsed voltages for electropermeabilization. The surface of the electrode is coated with a thin Au film to reduce impedance. The insulation layer contains holes aligned on the electrodes to constrict the electric field so that the applied voltage drops mainly at the hole and is effectively used for electropermeabilization. Adherent cells for electropermeabilization are cultured on the device and those in the vicinity of the holes are influenced by the relatively strong electric field induced by the holes in the insulation layer. We demonstrated the culture of adherent cells on the device and their optical observation by phase-contrast microscopy. We further demonstrated the delivery of YO-PRO-1 into various cells including HeLa, NIH3T3, and smooth muscle cells, by applying pulsed voltages of 6.0 V.