Fig. 2

Representative fluorescent figures of different cell models. Cells that were expressing fluorescent GFP protein were defined as successfully transfected (successful gene electrotransfer was achieved). Cells were grown: A and B in a monolayer, C and D on top of collagen layer and E and F embedded into collagen gel (3D model). Concentration of added pDNA in electroporation medium was 90 µg/ml (A–F). Images of gel before pulses were applied (A, C, E), while in B, D and F eight pulses with 5 ms duration, pulse repetition frequency of 1 Hz and E = 0.8 kV/cm were applied. To visualize cells, × 20 (A, B) or × 10 (C–F) objective magnification was used