Fig. 4
Comparative transfection efficiencies and cytotoxicities of lPEI/pDNA and bPEI/pDNA complexes delivered before mechanical cell stimulation (pre-delivery set-up). a Workflow of the pre-delivery vibropolyfection experimentation. Twenty-four hrs post-seeding, L929 cells were challenged with polyplexes, stimulated for 5 min at different frequencies (fin = 100 Hz, 500 Hz, and 1,000 Hz), then cultured for a further 24 hrs in standard culture conditions. Cytotoxicity and transfection efficiency were assessed 24 hrs after adding polyplexes to the cells. The transfection efficiency is expressed as b, d Gaussia luciferase activity and c, e fold-increase in Gaussia luciferase activity of vibropolyfected over polyfected cells (standard transfections), while f, g cytotoxicity is the percent cell toxicity (%) as compared to unstimulated and untransfected cells (CTRL). b, d, and f refer to lPEI/pGLuc (black bars), while (c, e, and g) to bPEI/pGLuc (gray bars) complexes. Each number within bars in the panels e and f refers to the average fold increase value. Results are expressed as mean ± SD (n ≥ 4; *p < 0.05)