Articles Dimerizable Cationic Detergents with a Low cmc Condense Plasmid DNA into Nanometric Particles and Transfect Cells in Culture Emmanuel Dauty, Jean-Serge Remy, Thomas Blessing, and Jean-Paul Behr* Contribution from the Laboratoire de Chimie Ge ´ ne ´ tique associe ´ CNRS/UniVersite ´ Louis Pasteur de Strasbourg, Faculte ´ de Pharmacie BP 24, 67401 Illkirch, France ReceiVed March 23, 2001 Abstract: The size of condensed DNA particles is a key determinant for in vivo diffusion and gene delivery to cells. Gene molecules can be individually compacted by cationic thiol detergents into nanometric particles that are stabilized by oxidative conversion of the detergent into a gemini lipid. To reach the other goal, gene delivery, a series of cationic thiol detergents with various chain lengths (C 12 -C 16 ) and headgroups (ornithine or spermine) was prepared, using a versatile polymer-supported synthetic strategy. Critical micelle concentrations and thiol oxidation rates of the detergents were measured. The formation and stability of complexes formed with plasmid DNA, as well as the size, -potential, morphology, and transfection efficiency of the particles were investigated. Using the tetradecane/ornithine detergent, a solution of 5.5 Kpb plasmid DNA molecules was converted into a homogeneous population of 35 nm particles. The same detergent, once oxidized, exhibited a typical lipid phase internal structure and was capable of effective cell transfection. The particle size did not increase with time. Surprisingly, the gel electrophoretic mobility of the DNA complexes was found to be higher than that of plasmid DNA itself. Favorable in vivo diffusion and intracellular trafficking properties may thus be expected for these complexes. Introduction Gene therapy relies on DNA-carrying vehicles. The course of a gene to the cell nucleus is a complex multistage process that requires a multicomponent particulate vector. Unfortunately, in vivo diffusion of such particles, whether nonreplicating viruses or simple DNA complexes, is severely restricted by their size. Synthetic supramolecular vectors are based on the DNA condensing property of cationic polymers or lipids. 1,2 Co- condensation of oppositely charged polymers is a quasi- irreversible process that leads to microprecipitates (hence, a convenient DNA isolation technique). 3 Particles are heteroge- neous with respect to composition, size (50-500 nm), and shape (toroids, rods, and their aggregates). 4 Additional aggregation occurs at physiological salt concentration, because of the fact that Coulombic repulsions become shielded by ions, thus making van der Waals attraction between particles predominant. Such * Corresponding author. E-mail: behr@aspirine.u-strasbg.fr. (1) Behr, J. P. Acc. Chem. Res. 1993, 26, 274-278. (2) Artificial Self-Assembling Systems for Gene DeliVery; Felgner, P. L., Heller, M. J., Lehn, P., Behr, J. P., Szoka, F. C., Eds.; American Chemical Society: Washington, D.C., 1996. (3) Sambrook, J.; Fritsch, E. F.; Maniatis, T. Molecular Cloning: A Laboratory Manual, 2nd ed.; Cold Spring Harbor Laboratory Press: Cold Spring Harbor, New York, 1989. (4) Xu, Y.; Szoka, F. C. Biochemistry 1996, 35, 5616-5623. VOLUME 123, NUMBER 38 SEPTEMBER 26, 2001 © Copyright 2001 by the American Chemical Society 10.1021/ja015867r CCC: $20.00 © 2001 American Chemical Society Published on Web 08/31/2001