Branched Amphipathic Peptide Capsules: Different Ratios of the Two Constituent Peptides Direct Distinct Bilayer Structures, Sizes, and DNA Transfection Efficiency

Branched amphipathic peptide capsules (BAPCs) are biologically derived, bilayer delimited, nanovesicles capable of being coated by or encapsulating a wide variety of solutes. The vesicles and their cargos are readily taken up by cells and become localized in the perinuclear region of cells. When BAPCs are mixed with DNA, the BAPCs act as cationic nucleation centers around which DNA winds. The BAPCs-DNA nanoparticles are capable of delivering plasmid DNA in vivo and in vitro yielding high transfection rates and minimal cytotoxicity. BAPCs share several biophysical properties with lipid vesicles. They are however considerably more stable-resisting disruption in the presence of chaotropes such as urea and guanidinium chloride, anionic detergents, proteases, and elevated temperature (similar to 95 degrees C). To date, all of our published results have utilized BAPCs that are composed of equimolar concentrations of the two branched sequences (Ac-FLIVI)(2)-K-K-4-CO-NH2 and (Ac-FLIVIGSII)(2)-K-K-4-CO-NH2. The mixture of sizes was utilized to relieve potential curvature strain in the spherical capsule. In this article, different molar ratios of the two peptides were studied to test whether alternate ratios produced BAPCs with different biological and biophysical properties. Additionally, preparation (annealing) temperature was included as a second variable.