Experimental and simulation studies of polyarginines across the membrane of giant unilamellar vesicles

Cell-penetrating peptides have widespread applications in biomedicine because of their capability to translocate across cell membranes alone or with cargos. Although endocytosis and direct penetration pathways have been reported, the translocation mechanism remains incompletely understood. In this study, we used giant unilamellar vesicles (GUVs) as the model membrane to investigate experimentally and numerically the interaction mechanism between polyarginine peptides and the lipid bilayer. Experimental results show that the introduction of negatively charged lipids into the GUV membrane improves the direct penetration of peptides, and molecular dynamics simulation results show that R8 peptides induce the formation of a hydrophilic hole on the membrane and penetrate through the hole with the cooperation effect. The R8-GUV interaction depends not only on electrostatic interaction but also on other interactions; specifically, the peptide cooperation effect and hydrophilic interaction also participate in peptide penetration. Our results provide extensive insight into the peptide penetration mechanism and suggestions for drug and gene delivery.