(A) Stability testing of untargeted polyplexes against phosphate-buffered saline (PBS). After 30 min of polyplex incubation (2 µg pDNA; N/P 12) in deionized water and addition of 500 µL PBS, DLS measurement was performed. Time points 0, 5, 30, 60, and 180 min were displayed. In case of colloidally-stable polyplexes of PEG24, PEG48, and PAS8, a measurement after 24 h is also displayed. Data are presented as mean value (±SD) out of triplets; (B) Polyplexes (2 µg pDNA; N/P 12) were incubated in HBG with or without 3 × 106 erythrocytes. After centrifugation, the supernatant was taken, and 3500 IU of heparin were added to release pDNA of the polyplexes. Cy5 fluorescence was compared to uncomplexed (free) pDNA. Statistical analysis (Student’s t-test): ns p > 0.05, * p ≤ 0.05; ** p ≤ 0.01.