title: Zeta potential changing phosphorylated nanocomplexes for pDNA delivery.
abstract: The objective of this study was to evaluate the suitability of a zeta potential changing system as gene delivery system. The phosphate ester bearing ligand 6-phosphogluconic acid (6-PGA) was attached to linear and branched polyethyleneimine (PEI) via a carbodiimide-mediated reaction whereby 287 μmol and 413 μmol 6-PGA could be coupled per gram polymer. Nanocomplexes of these modified polymers with pDNA showed a zeta potential of +12 mV for nanocomplexes with the linear PEI-6PGA and +16 mV in case of the branched derivative. By the addition of carboxymethylcellulose (CMC), zeta potentials of the complexes were reduced to +2.86 and +3.25, respectively. Phosphate release studies on Caco 2 cells and HEK-293 cells demonstrated the ability to cleave the phosphate ester. Compared to HEK-293 cells, enzymatic degradation of the phosphate ester in Caco 2 cells was 2.3-fold higher from nanocomplexes comprising linear PEI and 4.3-fold higher from those with branched PEI. Furthermore, incubation with alkaline phosphatase led to an increase in the zeta potential of nanocomplexes based on linear PEI-6PGA to +6.96mV and +8.26 mV in nanocomplexes comprising branched PEI-6PGA. Studying transfection efficiency in Caco 2 cells and HEK-293 cells, a higher expression of the green fluorescent protein (GFP) could be detected in HEK-293 cells. In presence of a phosphate inhibitor, transfection efficiencies were decreased in both cells lines, due to a lacking shift of the zeta potential of the tested pDNA complexes. According to these results, zeta potential changing systems seem to be a promising strategy for future gene delivery systems, as this concept allows the in situ generation of positive charges in close proximity to the cellular surface.
authors.affiliation: Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Sonja
authors.initials: S
authors.lastname: Bonengel
authors.affiliation: Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Felix
authors.initials: F
authors.lastname: Prüfert
authors.affiliation: Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria.
authors.forename: Max
authors.initials: M
authors.lastname: Jelkmann
authors.affiliation: Center for Chemistry and Biomedicine, Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria. Electronic address: andreas.bernkop@uibk.ac.at.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bernkop-Schnürch
mesh_terms: D018938:Caco-2 Cells; D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000008:administration & dosage* / Q000737:chemistry; D018014:Gene Transfer Techniques; D005942:Gluconates / Q000737:chemistry*; D049452:Green Fluorescent Proteins / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D010710:Phosphates / Q000378:metabolism; D010957:Plasmids; D011094:Polyethyleneimine / Q000737:chemistry*
chemical_list: D005942:Gluconates; D010710:Phosphates; D049452:Green Fluorescent Proteins; D011094:Polyethyleneimine; D004247:DNA; C008884:6-phosphogluconic acid
keywords: 6-; Phosphatase; Phosphogluconic acid; Polyethyleneimine; Zeta potential changing systems; pDNA