ARTICLE
Quantitative Measurement of Cationic Polymer Vector and PolymerpDNA Polyplex Intercalation into the Cell Plasma Membrane )
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Sriram Vaidyanathan,† Kevin B. Anderson,† Rachel L. Merzel,‡ Binyamin Jacobovitz,^ Milan P. Kaushik,‡ Christina N. Kelly,‡ Mallory A. van Dongen,‡ Casey A. Dougherty,‡ Bradford G. Orr,§, and Mark M. Banaszak Holl*,†,‡, ,^ †
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Departments of Biomedical Engineering, ‡Chemistry, and §Physics, and the Programs in Applied Physics and ^Biophysics, University of Michigan, Ann Arbor, Michigan 48109, United States
ABSTRACT Cationic gene delivery agents (vectors) are important for delivering nucleotides, but are
also responsible for cytotoxicity. Cationic polymers (L-PEI, jetPEI, and G5 PAMAM) at 1 to 100 the concentrations required for translational activity (protein expression) induced the same increase in plasma membrane current of HEK 293A cells (3050 nA) as measured by whole cell patch-clamp. This indicates saturation of the cell membrane by the cationic polymers. The increased currents induced by the polymers are not reversible for over 15 min. Irreversibility on this time scale is consistent with a polymer-supported pore or carpet model and indicates that the cell is unable to clear the polymer from the membrane. For polyplexes, although the charge concentration was the same (at N/P ratio of 10:1), G5 PAMAM and jetPEI polyplexes induced a much larger current increase (40- 50 nA) than L-PEI polyplexes (
