Arginine
(Arg)-rich cell-penetrating peptides (CPPs) are promising
tools for plasmid DNA (pDNA) delivery. α-Aminoisobutyric acid
(Aib) is known to stabilize peptide helical secondary structures and
has been used as a building block for foldamers. In the current study,
we prepared Aib CPP foldamers, (Arg–Arg–Aib)
n
(n = 1–6) and examined their
pDNA transfection abilities. Transfection efficiencies of peptide/pDNA
complexes are dependent on peptide chain length, with longer peptides
(n ≥ 4) exhibiting better transfection abilities
than an Arg nonapeptide. Furthermore, Aib CPP foldamers achieve prolonged
transfection abilities compared with commercially available transfection
reagents, which is probably because of the high resistance of the
peptides to enzymatic degradation, thereby protecting the encapsulated
pDNA for a long period. The obtained results demonstrated promising
features of Aib CPP foldamers as pDNA delivery carriers.