Fig. 4

Evaluation of cytotoxicity and hemocompatibility of PBMD(pDNA) particles without (PBMD) and with shielding and control polymers (+ PNC, + PNAM, + PCEAm) at L/C 0.6. Cytotoxicity was investigated by measuring A the metabolic activity (PrestoBlue™ assay) and B LDH release to evaluate membrane integrity (Cytotox-ONE™ assay). HEK293T cells were incubated for 4 h with the particles and subsequently for 20 h in fresh media, K-562 for 24 h with the particles without media change. Data are presented as single measurement points and were fitted using either logistic or linear functions (n ≥ 3). Statistical significant differences in comparison to the naked PBMD (pDNA) particle at the respective concentration is denoted as follows: *p < 0.05, **p < 0.01, and ***p < 0.001. C Hemolytic activity was measured as release of hemoglobin from human erythrocytes after incubation with the particles. Human erythrocytes were incubated with the particles at pH 7.4 and 6 to mimic conditions present in the blood and the endosomes respectively (n = 3 ± SD). Statistical significant differences in comparison to the naked PBMD(pDNA) particle at the respective concentration and pH value is denoted as follows: *p < 0.05, **p < 0.01, and ***p < 0.001