Hybrid Cell-Penetrating Foldamer with Superior Intracellular Delivery Properties and Serum Stability

Abstract

Sequence specific molecules with high folding ability (i.e. foldamers) can be used to precisely control the distribution and projection of side chains in space and have recently been introduced as tailored systems for delivering nucleic acids into cells. Designed oligourea sequences with an amphipathic distribution of Arg-and His-type residues were shown to form tight complexes with plasmid DNA, and to effectively promote the release of DNA from the endosomes. Herein, we report the synthesis of new cell-penetrating foldamer sequences in which the foldamer segment is conjugated via a reducible disulfide bond to a ligand that binds cell-surface expressed nucleoproteins with the idea that this system could facilitate both assemblies with nucleic acids and cell entry. This new system was evaluated for delivery of DNA in several cell lines and was found to compare favorably with all comparators tested (DOTAP and b-PEI as well as a number of known cell penetrating peptides) in various cell lines and particularly in culture medium containing up to 50% of serum. These results suggest that this dual molecular platform which is long lasting and non-cytotoxic could be of practical use for in vivo applications.

Characterization of the DNA and Membrane Interactions of a Bioreducible Cell-Penetrating Foldamer in its Monomeric and Dimeric Form

“…S3). Indeed, recently it has been demonstrated that related disulfide-conjugated complexes exhibit increased stability in biological fluids 25 . In contrast, a high density of free -SH during the foldaplex assembly process may even result in a templating effect that trigger its oxidation into dimer 50 thereby explaining the much higher activity of 3-SH when compared to 3 at high 3-SH/DNA mass ratio ( Figure S3).…”

“…Recently, oligourea foldamers were designed and tested that followed the same concepts which helped to develop the LAH4 transfection compounds 24,25 . Oligourea foldamers are characterized by a pronounced propensity to form stable helices in both organic secondary structures.…”

De Novo Design of Cell‐Penetrating Foldamers

“…Furthermore, the disulfide conjugation of oligourea molecules to nucleolin increased the ability of the resultant molecule to deliver pDNA into cells in 50 % serum-containing media. [74] 9. Peptoids N-Substituted polyglycines are referred to as peptoids, which have been investigated as peptide mimetics.…”

Different Biological Activities of Histidine-Rich Peptides Are Favored by Variations in Their Design

“…Chemical and biochemical reactions of amino acid side chains or termini that reproduce or mimic the naturally occurring posttranslational modifications of polypeptides, such as acetylation or phosphorylation, as well as the incorporation of non-natural amino acids further enhance the range of structures with highly variable characteristics. Furthermore, molecules have been created that represent the physico-chemical properties of known peptides [4][5][6][7]. These have been Toxins 2021, 13, 363 2 of 15 designed to be less prone to proteolytic degradation, thereby further expanding the range of possible applications.…”