biostudies-literatureLeng QNIBIB NIH HHSNational Institutes of HealthNational Institute of Biomedical Imaging and Bioengineering150566https://www.ebi.ac.uk/biostudies/studies/S-EPMC11568931biostudies-literatureUnknown738Cationic polymers that bind with the plasmids to form polyplexes protect the DNA from enzymatic degradation and improve cellular and tissue uptake. Complete or near complete gel retardation of the polyplex is an important assay to determine the optimal polymer: plasmid ratio for in vitro and in vivo studies. Nevertheless, despite minimal to moderate gel retardation of histidine-lysine (HK) polyplexes formed with low peptide: plasmid DNA ratios (1:2 and 1:4; w:w), the polyplexes effectively targeted the tumor in vivo. To understand the lack of predictability of the initial gel mobility shift assays, we revisited the retardation and stability of polyplexes with these electrophoresis assays. Because the histidine component with a pKa of about 6.0 will have a greater positive charge and may biBiochemical and biophysical research communicationspH modification of gel mobility shift improves polyplex selection In Vivo.PMC11568931R01-EB028534R01 EB028534Leng QMixson AJAnand AfalsepH modification of gel mobility shift improves polyplex selection In Vivo.Cationic polymers that bind with the plasmids to form polyplexes protect the DNA from enzymatic degradation and improve cellular and tissue uptake. Complete or near complete gel retardation of the polyplex is an important assay to determine the optimal polymer: plasmid ratio for in vitro and in vivo studies. Nevertheless, despite minimal to moderate gel retardation of histidine-lysine (HK) polyplexes formed with low peptide: plasmid DNA ratios (1:2 and 1:4; w:w), the polyplexes effectively targeted the tumor in vivo. To understand the lack of predictability of the initial gel mobility shift assays, we revisited the retardation and stability of polyplexes with these electrophoresis assays. Because the histidine component with a pKa of about 6.0 will have a greater positive charge and may bi2024-01-01T00:00:00Z2024 Dec2026-06-06T03:51:21.738Z2026-05-25T03:12:07.225ZS-EPMC115689313918089210.1016/j.bbrc.2024.150566