title: Quantifying the Interactions between PEI and Double-Stranded DNA: Toward the Understanding of the Role of PEI in Gene Delivery.
abstract: Poly(ethylene imine) (PEI) is one of the most efficient nonviral vectors, and its binding mode/strength with double-stranded DNA (dsDNA), which is still not clear, is a core area of transfection studies. In this work we used the atomic force microscopy (AFM)-based single molecule force spectroscopy (SMFS) to detect the interaction between branched PEI and dsDNA quantitatively by using a long chain DNA as a probe. Our results indicate that PEI binds to phosphoric acid skeletons of dsDNA mainly via electrostatic interactions, no obvious groove-binding or intercalation has happened. The interaction strength is about 24-25 pN, and it remains unchanged at pH 5.0 and 7.4, which correspond to the pH values in lysosomes and in the cytoplasmic matrix, respectively. However, the interaction is found to be sensitive to the ionic strength of the environment. In addition, the unbinding force shows no obvious loading rate dependence indicative of equilibrium binding/unbinding.
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Kou
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University , Changchun 130012, People's Republic of China.
authors.forename: Wenke
authors.initials: W
authors.lastname: Zhang
mesh_terms: D004247:DNA / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D009994:Osmolar Concentration; D011094:Polyethyleneimine; D014162:Transfection
chemical_list: D011094:Polyethyleneimine; D004247:DNA
keywords: AFM; DNA; nonviral vectors; poly(ethylene imine); single molecule force spectroscopy