Development of plasmid and oligonucleotide nanometric particles.

Nucleic acids delivery vectors have shown promising therapeutic potential in model systems. However, comparable clinical success is delayed essentially because of their poor biodistribution and of their ineffective intracellular trafficking. The size of condensed DNA particles is a key determinant for in vivo diffusion, as well as for gene delivery to the cell nucleus. Towards this goal, we have developed cationic thiol-detergents that individually compact plasmid DNA molecules into anionic particles. These particles are then 'stabilized' by air-induced dimerization of the detergent into a disulfide lipid on the template DNA. The particles all measure approximately 30 nm, which corresponds to the volume of a single molecule of plasmid DNA. The gel electrophoretic mobility of the anionic particles was found to be higher than that of the plasmid DNA itself. Similarly, particles formed with a 31-mer oligonucleotide measured 19 nm. Improved in vivo diffusion, as well as improved intracellular trafficking may be inferred from the faster migration of the complexes. Moreover, the size of the particles remains compatible with nuclear pore crossing. Finally, in an attempt to improve the biodistribution of these particles, we have coated the monomolecular particles with a poly(ethylene glycol) corona.