DSPE-PEG1000-GALA is a PEG compound composed of DSPE and the pulmonary endothelial-targeting peptide GALA. GALA is a pH-responsive amphipathic peptide consisting of 30 amino acids, serving as a pulmonary endothelial-targeting ligand. In an acidic environment with a pH of 5.0, GALA undergoes a conformational change from random coil to α-helix, which induces destabilization and fusion of endosomal membranes. Liposomes modified with GALA facilitate transcytosis across pulmonary endothelial cells via clathrin-dependent endocytosis and accumulate specifically in the lungs following intravenous injection. DSPE-PEG1000-GALA is applicable for drug delivery.