DSPE-Hydrazone-mPEG (MW 3.4K) is a pH-responsive phospholipid-PEG conjugate with a 3400 Da mPEG chain and a cleavable hydrazone bond. It is amphiphilic, forms stable micelles/liposomes, and releases payloads rapidly in acidic endo/lysosomal environments. Used for pH-triggered targeted drug delivery and long-circulating nanocarriers.