DSPE-PEG3400-GALA is a PEG compound composed of DSPE and the lung endothelial-targeting peptide GALA. GALA is an amphiphilic pH-responsive peptide consisting of 30 amino acids, acting as a ligand targeting lung endothelium. In acidic environments of pH 5.0, GALA undergoes a conformational change from random coil to α-helix, inducing destabilization and fusion of the endosomal membrane. Liposomes modified with GALA cross lung endothelial cells through clathrin-dependent endocytosis and transcytosis and specifically accumulate in the lungs following intravenous injection. DSPE-PEG3400-GALA is applicable for drug delivery.