The invention relates to novel materials based on biodegradable polyamino acids, particularly useful for the vectorisation of active principals (PA). The invention further relates to novel, pharmaceutical, cosmetic, dietary or phytosanitary compositions. The invention provides novel polymeric raw material, for use in the vectorisation of PA and with an optimal match for all the requirements of the type: biocompatibility, biodegradability, stability, ability to easily associate with numerous active principals or to solubilise the same and to liberate said active principals in vivo. Said aim is achieved with polyamino acids comprising aspartic and/or glutamate units, some of which carry at least one graft, characterised in that at least one of said grafts is bonded to an aspartic or glutamate unit by means of an amino acids spacer based on Leu, and/or Ileu, and/or Val, and/or Phe and a hydrophobic group with C6-C30 is connected by an ester bond to the spacer.
