DNA transfection using linear poly(ethylenimine) prepared by controlled acid hydrolysis of poly(2-ethyl-2-oxazoline)

A series of linear poly(ethylenimine) (L-PEI) containing varying amounts of cationic charge density in its backbone was produced by controlled hydroly sis of poly(2-ethyl-2-oxazoline) (PEtOz) for using as a nonviral DNA transf ection agent. The effects of cationic charge density and molecular weight o f the L-PEI on the cytotoxicity and transfection efficiency were studied. T he efficiency of transfection was monitored by using a luciferase reporter gene system. Gel retardation assay and dynamic light scattering (DLS) showe d that the condensation capacity of L-PEI was suitable for transfection. Hi ghly compacted L-PEI/DNA complex (similar to 150 nm) was obtained with a su rface charge value of around +28.4 mV. Cell cytotoxicity was affected to a great extent by the hydrolysis percent of L-PEI as well as by the molecular weight. Transfection efficiency of luciferase plasmid DNA against NIH 3T3 fibroblast was largely dependent upon the hydrolysis percent (charge densit y) in the polymer backbone and the molecular weight of the L-PEI, but indep endent of the total amount of cationic charges used for DNA condensation. L -PEI with a hydrolysis percent of 88.0% exhibited comparable transfection e fficiency to that of commonly used branched PEI. (C) 2001 Elsevier Science B.V. All rights reserved.