Abstract: Compositions and methods for delivering non-anionic polynucleotide analog cargoes to the cytosolic/nuclear compartment of eukaryotic cells via a synthetic peptide shuttle agent are described herein. The non-anionic polynucleotide analog cargoes may be charge-neutral or cationic, and the synthetic peptide shuttle agent is a peptide comprising an amphipathic alpha-helical motif having both a positively-charged hydrophilic outer face and a hydrophobic outer face, wherein synthetic peptide shuttle agent is not covalently linked, or linked in a cleavable manner under physiological conditions, to the non-anionic polynucleotide analog cargoes. The non-anionic polynucleotide analog cargo may be a charge-neutral or cationic antisense synthetic oligonucleotide (ASO) that hybridizes to an intracellular target RNA for gene expression modification.

Abstract: Described herein are methods, compositions, kits and synthetic peptide shuttle agents relating to the transduction of proteinaceous and/or non-proteinaceous cargoes. The method generally comprises contacting target eukaryotic cells with a non-proteinaceous cargo and a concentration of a synthetic peptide shuttle agent sufficient to increase the transduction efficiency of the non-proteinaceous cargo, as compared to in the absence of said synthetic peptide shuttle agent. In embodiments, the non-proteinaceous cargo may be a drug, such as a small molecule drug, for treating a disease. In other embodiments, novel synthetic peptide shuttle agents having transduction activity for proteinaceous and/or non-proteinaceous cargoes are described, as well as the use of propidium iodide or other membrane-impermeable fluorescent DNA intercalating agent as a surrogate cargo for selecting versatile synthetic peptide shuttle agents having transduction activity for both proteinaceous and non-proteinaceous cargoes.