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Figure 3: Optimization of CD133+ transfection using different compositions of miR/PEI/MNP complexes. Cells were transfected with Cy3-labeled complexes consisting of 20 pmol miR, three different N/P ratios (2.5, 5, and 7.5), and six different MNP amounts (0, 1, 2, 3, 4, and 5 μg/mL). Representative images confirming intracellular localisation of complexes were taken 18 h after transfection using laser scanning confocal microscopy (a). Uptake efficiency (b) and cytotoxicity (c) were measured 18 h after transfection by flow cytometry. Untransfected cells were used as control. Values are presented as mean ± SEM; ; statistic was performed versus 20 pmol miR, N/P ratio 2.5 with respective MNP amount (indicated as ) or within the same N/P ratio (a) and versus control (b); ; ; . Scale bar = 50 μm.