Figure 7.

Spatially restricted gene transfer. HEK293 cells were seeded on the plasmid-arrayed electrode, cultured for 24 h, and then treated with a single electric pulse at the field strength of 75 V/cm for 10 ms duration. Fluorescence images were acquired 48 h after electric pulsing. (A) Fluorescence image showing EGFP expression in the restricted regions of HEK293 cells 48 h after electric pulsing. Note that cells are adhered to the entire surface of the electrode, while fluorescently active cells are observed only in the plasmid-loaded square islands. (B) Fluorescence image of HEK293 cells transfected on the electrode with a plasmid-loaded island array prepared using the poly(ethylene glycol)-tethering alkanethiol. (C) Higher magnification image of (B). (D) Phase-contrast image of (C). Note that cells adhere only on the islands but not on the surrounding regions. Scale bar: (A and B) 1 mm; (C and D) 200 μm.