The transferrin (TfR) and epidermal growth factor receptors (EGFR) are known to be\noverexpressed on the surface of a wide variety of tumor cells. Therefore, the peptides B6 (TfR\nspecific) and GE11 (targeted to the EGFR) were linked to the PAMAM (polyamidoamine) structure\nvia a polyethylenglycol (PEG) 2 kDa chain with the aim of improving the silencing capacity of\nthe PAMAM-based dendriplexes. The complexes showed an excellent binding capacity to the\nsiRNA with a maximal condensation at nitrogen/phosphate (N/P) 2. The nanoparticles formed\nexhibited hydrodynamic diameters below 200 nm. The zeta potential was always positive, despite\nthe complexes containing the PEG chain in the structure showing a drop of the values due to the\nshielding effect. The gene silencing capacity was assayed in HeLa and LS174T cells stably transfected\nwith the eGFPLuc cassette. The dendriplexes containing a specific anti luciferase siRNA, assayed at\ndifferent N/P ratios, were able to mediate a mean decrease of the luciferase expression values of 14%\nfor HeLa and 20% in LS174T cells, compared to an unspecific siRNA-control. (p < 0.05). In all the\nconditions assayed, dendriplexes resulted to be non-toxic and viability was always above 75%.
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