The invention relates to novel biodegradable materials which are based on modified polyamino acids and which can be used for the vectorisation of active principle(s) (AP). The invention also relates to novel pharmaceutical, cosmetic, dietary or phytosanitary compositions based on said polyamino acids. The aim of the invention is to provide a novel polymer raw material which can be used for the vectorisation of active principles and which can optimally fulfil all required specifications in said area, namely: biocompatibility, biodegradability and the ability to become easily associated with many active principles or to solubilise said principles and to release same in vivo. Said aim is achieved with novel copolyhydroxyalkylglutamines comprising glutamine units and optionally glutamate units and bearing hydrophobic groups containing between 8 and 30 carbon atoms. Said copolyhydroxyalkylglutamines are amphiphilic and can be easily and economically transformed into particles for the vectorisation of active principles, whereby said particles can form stable aqueous colloidal suspensions.