DSPE-PEG-SH (MW 2000) is a polyethylene glycol-modified phospholipid with a terminal reactive thiol group capable of forming covalent thioether linkages with Maleimide-containing molecules. DSPE-PEG-SH (MW 2000) self-assembles into amphiphilic lipid bilayers in aqueous solutions and is employed in drug delivery research, including the encapsulation of nucleic acids, peptides, and small molecules, as well as in mRNA vaccine formulations.