Polyamine-DNA interactions and development of gene delivery vehicles.

Polyamines are positively charged organic cations under physiologic ionic and pH conditions and hence they interact with negatively charged macromolecules such as DNA and RNA. Although electrostatic interaction is the predominant mode of polyamine-nucleic acid interactions, site- and structure-specific binding has also been recognized. A major consequence of polyamine-DNA interaction is the collapse of DNA to nanoparticles of approximately 100 nm diameter. Electron and atomic force microscopic studies have shown that these nanoparticles are spheroids, toroids and rods. DNA transport to cells for gene therapy applications requires the condensation of DNA to nanoparticles and hence the study of polyamines and related compounds with nucleic acids has received technological importance. In addition to natural and synthetic polyamines, several amine-terminated or polyamine-substituted agents are under intense investigation for non-viral gene delivery vehicles.