Effects of cargo molecules on membrane perturbation caused by transportan10 based cell-penetrating peptides

Cell-penetrating peptides with the ability to escape endosomes and reach the target are of great value as delivery vectors for different bioactive cargoes and future treatment of human diseases. We have studied two such peptides, NickFect1 and NickFect51, both originated from stearylated transportan10 (PF3). To obtain more insight into the mechanism(s) of peptide delivery and the biophysical properties of an efficient vector system, we investigated the effect of different bioactive oligonucleotide cargoes on peptide-membrane perturbation and peptide structural induction. We studied the membrane interactions of the peptides with large unilamellar vesicles and compared their effects with parent peptides transportan10 and PF3. In addition, cellular uptake and peptide-mediated oligonucleotide delivery were analyzed. Calcein leakage experiments showed that similar to transportan10, NickFect51 caused a significant degree of membrane leakage, whereas NickFect1, similar to PF3, was less membrane perturbing. The results are in agreement with previously published results indicating that NickFect51 is a more efficient endosomal escaper. However, the presence of a large cargo like plasmid DNA inhibited NickFect's membrane perturbation and cellular uptake efficiency of the peptide was reduced. We conclude that the pathway for cellular uptake of peptide complexes is cargo dependent, whereas the endosomal escape efficacy depends on peptide hydrophobicity and chemical structure. For small interfering RNA delivery, NickFect51 appears to be optimal. The biophysical signature shows that the peptide alone causes membrane perturbation, but the cargo complex does not. These two biophysical characteristics of the peptide and its cargo complex may be the signature of an efficient delivery vector system.