Design, synthesis and evaluation of spermine-based pH-sensitive amphiphilic gene delivery systems: Multifunctional non-viral gene carriers

Abstract

Design and development of efficient non-viral gene delivery systems is critical to overcome various barriers for effective intracellular gene delivery. Eight new spermine-based protonatable surfactants were designed, synthesized and evaluated as non-viral pH-sensitive gene carriers. These carriers formed stable complexes with plasmid DNA at an N/P ratio as low as 2. The sizes of the carrier/pDNA nanoparticles (N/P = 12) were in the range of 90–130 nm, smaller than that of Lipofectamine-2000/pDNA nanoparticles. The pDNA nanoparticles of the carriers exhibited substantially increased hemolysis when pH decreased from 7.4 to 5.5. The DNA nanoparticles had low cytotocixity, similar to that of Lipofectamine-2000/pDNA nanoparticles. The pH-sensitive gene carriers with no helper lipids resulted in much higher intracellular transfection and gene expression in U87 cells than Lipofectamine-2000. [N,N′-Bis(oleoylcysteinyl)(β-alanyl-α-lysyl)]-spermine monoamide (SKACO) resulted in the highest luciferase transfection efficiency, more than 400 times higher than that of Lipofectamine-2000, and GFP expression in 71% of transfected U87 cells. SKACO was identified as a promising lead carrier for efficient gene delivery. These spermine-based pH-sensitive amphiphilic carriers have a potential to be further developed as efficient non-viral multifunctional gene delivery systems.