Clickable functionalization of liposomes with gH625 peptide from Herpes simplex virus type I for intracellular delivery

Liposomes externally modified with the nineteen residues gH625 peptide, previously identified as a membrane-perturbing domain in the gH glycoprotein of Herpes simplex virus type I, have been prepared in order to improve intracellular uptake of an encapsulated drug. An easy and versatile synthetic strategy, based on click chemistry, has been used to bind, in a controlled way, several copies of the hydrophobic gH625 peptide on the external surface of DOPG based liposomes. Electron Paramagnetic Resonance (EPR) studies, on liposomes derivatized with gH625 peptides modified with the TOAC spin label in several peptide positions, confirm the positioning of the coupled peptides on the liposome external surface, while DLS measurements indicate an increase of liposomes diameter of approximately 30% after peptide introduction. Liposomes have been loaded with the cytotoxic doxorubicin drug and their ability to penetrate inside cells has been evaluated by confocal microscopy experiments. Results suggest that liposomes functionalized with gH625 may act as promising intracellular targeting carriers for efficient delivery of drugs, such as chemotherapeutic agents, into tumor cells.