Figure 3.

DNA binding affinity of PBAEs is influenced strongly by pH. Yo-Pro-1 fluorophore binding assay with A) PBAE 447 B) PBAE 746 and C) BPEI demonstrate the difference in pH responsiveness of these polymers in regard to DNA binding. D) The calculated effective N/P ratio to quench Yo-Pro-1 fluorescence by 50% (EQ50) at each pH. PBAE 447 binding capacity for plasmid DNA increased by 100-fold between pH 4 and pH 8, whereas BPEI’s binding capacity for DNA increased by only 2-fold. Error bars show mean ± SD of four wells.