The present invention relates to the preparation and use of reversibly PEGylated nanocarriers. The reversibly PEGgylated nanocarrier system comprises an inner core comprising or consisting of a nanoparticle and/or at least one pharmaceutical compound； optionally at least one lipid bilayer on the surface of the inner core； a first ligand bound to the surface of said inner core, or if present, to the surface of the at least one lipid bilayer； a second ligand bound to the first ligand, the second ligand being covalently bound to poly(ethylene glycol) or a derivative thereof. The reversibly PEGgylated nanocarrier system is characterized in that binding of the second ligand to the first ligand is non-covalent and reversible. Pharmaceutical compositions and use of such compounds and compositions in the field of e.g. cancer therapy, gene therapy, inflammatory diseases and pain therapy are also disclosed.
