title: Change in size, morphology and stability of DNA polyplexes with hyperbranched poly(ethyleneimines) containing bulky maltose units.
abstract: Polyplexes between Salmon DNA and non-modified hyperbranched poly(ethyleneimines) of varying molar mass, i.e., PEI(5 k) with 5000 g/mol and PEI(25 k) with 25,000 g/mol, and modified PEI(5 k) with maltose units (PEI-Mal) were investigated in dependence on the molar N/P ratio by using dynamic light scattering (DLS), zeta potential measurements, micro differential scanning calorimetry (μ-DSC), scanning-transmission electron microscopy (STEM), and cryo-scanning electron microscopy (cryo-SEM). A reloading of the polyplexes can be observed by adding the unmodified PEI samples of different molar mass. In excess of PEI a morphological transition from core-shell particles (at N/P 8) to loosely packed onion-like polyplexes (at N/P 40) is observed. The shift of the DSC melting peak from 88 °C to 76 °C indicates a destabilization of the DNA double helix due to the complexation with the unmodified PEI. Experiments with the maltose-modified PEI show a reloading already at a lower N/P ratio. Due to the presence of the sugar units in the periphery of the polycation electrostatic interactions between DNA become weaker, but cooperative H-bonding forces are reinforced. The resulting less-toxic, more compact polyplexes in excess of the PEI-Mal with two melting points and well distributed DNA segments are of special interest for extended gene delivery experiments.
authors.affiliation: Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Rumschöttel
authors.affiliation: Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Kosmella
authors.affiliation: Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Prietzel
authors.affiliation: Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, 01069 Dresden, Germany.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Appelhans
authors.affiliation: Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany. Electronic address: koetz@uni-potsdam.de.
authors.forename: Joachim
authors.initials: J
authors.lastname: Koetz
mesh_terms: D002152:Calorimetry, Differential Scanning; D020285:Cryoelectron Microscopy; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D000067493:Dynamic Light Scattering; D006860:Hydrogen Bonding; D046911:Macromolecular Substances / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D008320:Maltose / Q000737:chemistry* / Q000378:metabolism; D017348:Microscopy, Electron, Scanning Transmission; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D010316:Particle Size; D011094:Polyethyleneimine / Q000737:chemistry* / Q000378:metabolism; D011199:Potentiometry; D055672:Static Electricity; D044366:Transition Temperature
chemical_list: D046911:Macromolecular Substances; D008320:Maltose; D011094:Polyethyleneimine; D004247:DNA
keywords: DNA complexation; Maltose-modified poly(ethyleneimine); Morphology; Polyplexes