Protection of P123-polyethylenimine (PEI)-R13 on plasmid DNA. (A) Protection of plasmid DNA from degradation by DNase I at varying concentrations of 0 DNase I/μg DNA, 0.15 DNase I/μg DNA, 0.375 DNase I/μg DNA, 0.75 DNase I/μg DNA, 1.5 DNase I/μg DNA, 2.25 DNase I/μg DNA, 3 DNase I/μg DNA, 3.75 DNase I/μg DNA, 4.5 DNase I/μg DNA, 5.25 DNase I/μg DNA, 6 DNase I/μg DNA, 6.75 DNase I/μg DNA, and 7.5 U DNase I/μg DNA. (B) Protection of plasmid DNA from dissociation by serum at varying concentrations of 10%, 25%, and 50%. The lanes 10%, 25%, and 50% without “+” refer to the presence of only 10%, 25%, and 50% serum. The lanes 10%, 25%, and 50% with “+” refer to the presence of P123-PEI-R13/DNA complexes at w/w ratio 20 with different concentration of serum. (C) Protection of plasmid DNA from dissociation by sodium heparin at varying concentrations of 0 μg/mL, 120 μg/mL, 140 μg/mL, 160 μg/mL, 180 μg/mL, 200 μg/mL, 220 μg/mL, 240 μg/mL, 260 μg/mL, 280 μg/mL, 300 μg/mL, 400 μg/mL, 500 μg/mL, and 600 μg/mL.