Effect of molecular weight on the transfection efficiency of novel polyurethane as a biodegradable gene vector.

New polyurethane 2-diethylaminoethylamine-polyurethane (LGEA-PU) containing poly(ethylene glycol) segments and tertiary amines was synthesized. LGEA-PU self-assembled readily with the plasmid DNA (pCMV-betagal) in HEPES buffer and was characterized by dynamic light scattering, zeta potential, atomic force microscopy, and XTT cell viability assays. To examine the effect of molecular weight of LGEA-PU systems on transfection, LGEA-PU systems of four different molecular weights (LGEA-PU99, LGEA-PU59, LGEA-PU24, and LGEA-PU7) were prepared. This study found that LGEA-PU99, LGEA-PU59, and LGEA-PU24 were able to bind plasmid DNA and yielded positively charged complexes with a nano-sized transfection (<200 nm). The LGEA-PU59/DNA complexes were able to transfect COS-7 cells in vitro with higher transfection efficiency than the other LGEA-PU systems. These results demonstrated that molecular weights of LGEA-PU systems had a significant effect on transferring ability, except for LGEA-PU99, which showed the strongest DNA condensation. Examination of the cytotoxicity of PEI and LGEA-PU systems revealed that LGEA-PU systems had lower cytotoxicity. In this article, LGEA-PU59 seemed to be a novel cationic polyurethane for gene delivery and an interesting candidate for further study.