In siRNA/DNA/polymer (PEI or P(SiDAAr)5P3) polyplexes, Ø-pDNA significantly enhanced luc-siRNA's transfection levels in MDA-MB-231-luc-D3H2LN cell line. In this condition, P(SiDAAr)5P3 is a more effective transfection agent compared to PEI. Data as mean ± standard deviation (n=2). †: statistically significant compared to PEI polyplexes of the same weight ratio. *, † p≤0.05; **, †† p≤0.01; ***, ††† p≤0.001.