Book of Abstracts: Albany 2003
June 17-21 2003
On the Structural ? Gene Transfer Activity Relationship of DNA-Dicationic Lipid Genosomes
A novel type of dicationic lipid (DCL) based on L-Glutamic acid, with different spacer arms between the two polar heads of lipid chain groups, was recently synthesized (1). The potential of Cationic liposomes, prepared from the DCL, for gene delivery was tested by monitoring gene expression in human cancerous cells (SKOV-3). Besides, the conformational and structural peculiarities of DNA-DCL complexes were studied using Atomic Force Microscopy (AFM). It is shown, that liposomes from DCL with short spacers form morphologically more compact particles with plasmid DNA of spherical and toroidal form (100-150 nm in diameter) and effectively transfer functional genes in eukaryotic cellular lines; while those with long spacers form unstable amorphous aggregates and were not potent for cell transfection. Moreover, Coherent Phase Microscopy was applied to study the DNA-DCL complex formation. Encapsulation of DNA molecules by the cationic liposomes, and a significant increase in the optical density and phase height were observed for the complex, compared to individual liposomes. The incubation time was found to play an important role in the condensation of DNA molecules by the cationic lipid. The size distribution for the DNA-DCL complexes at different L/D mass ratios was obtained using Dynamic light scattering (DLS), and was found to be consistent with the theoretical predictions for the isoelectric point of the system.
A. S. Elkady1,4,*