Abstract: The present invention relates to the field of drug delivery nanosystems. More precisely, the present invention concerns a copolymer with advantageous properties for the outer coating of various nanoparticles. Said copolymer comprises at least three types of monomers with stealthy, coupling and therapeutic properties respectively, as well as an optional fourth type of monomers with targeting properties. The present invention also relates to core-shell or hollow shell nanoparticles coated by an external layer of the copolymer according to the invention. Several types of core-shell nanoparticles are envisaged. The invention also concerns methods for preparing said nanoparticles, as well as pharmaceutical compositions or medicaments comprising them.