Improved Intracellular Delivery of Polyarginine Peptides with Cargoes

Abstract

Complementary to endocytosis, cell-penetrating peptides (CPPs) at high concentrations can penetrate the cell membrane in a direct way, which further makes CPPs popular candidates for delivering therapeutic or diagnostic agents. Although featured as rapid uptake, the translocation efficiency and potential toxicity of the direct penetration are usually affected by cargoes, which is still unclear. Here, using coarse-grained molecular dynamics simulations, we show that the polyarginine (R8) peptides penetrate the membrane through a water pore in the membrane, and the transmembrane efficiency is improved by conjugating to small nanoparticles (NPs) with proper linkers. It can be attributed to both the extension of the lifetime of the water pore by the NPs and outward diffusion of negative lipids in the asymmetry membrane, which induces the surrounding R8–NP conjugates to the water pore before it is closed. The translocation efficiency is closely related to the length of the linkers, and it gets the maximum value when the length of the linkers is around half of the membrane thickness. Overlong linkers not only decrease the transmembrane efficiency because of the blockage of NPs in the water pore but may also cause cytotoxicity because of the unclosed water pore. The results provide insights into the internalization of CPPs and facilitate the design of CPP and drug conjugates with high efficiency and low toxicity.

How arginine derivatives alter the stability of lipid membranes: dissecting the roles of side chains, backbone and termini

“…Further, continuum models (Ramírez et al 2019) as well as simulations with the MARTINI coarse-grained force field were used to study membrane-active peptides. Hu et al suggested that R 8 favors pore formation in asymmetric lipid bilayers, with 50% PS in their inner leaflet and the rest of the bilayer consisting of DMPC (Hu et al 2019). However, the MARTINI coarse-grained force field models electrostatic interactions and hydrogen bonds only qualitatively, which likely play a critical role for arginine-membrane interactions.…”

Brain penetrating peptides and peptide–drug conjugates to overcome the blood–brain barrier and target CNS diseases

“…Polyarginine peptides, such as R8, R11, and R18, are arginine‐rich CPPs that are protonated at physiological conditions and strongly interact with negatively charged carboxylic, sulfate, and phosphate groups of phospholipid membranes, distorting the membrane structure and initiating a hydrophilic water pore to be translocated in the membrane that leads to receptor‐independent cellular internalization (Hu et al, 2019; Nakase et al, 2004, 2008). Polyarginine CPPs can facilitate the transport of molecular cargoes including nucleic acids, active proteins, quantum dots, and nanoparticles across the membranes (Nakase et al, 2004; Robison et al, 2016).…”

pH-Responsive Polypeptide-Based Smart Nano-Carriers for Theranostic Applications

“…Junmei et al showed that pArg penetrated the membrane through a water pore on the membrane and by conjugating to small NPs with proper linkers, its transmembrane efficacy could be enhanced. The length of the linker around half of the membrane thickness was proper to get the maximum translocation efficiency [117]. Transdermal delivery of triptolide has been reported with C-14-hydroxyl group of triptolide modified with pArg [118].…”