The invention relates to 3-arms star-shaped polyglutamic derivatives which are able to self-assemble to form bioresponsive nanometric globular structures with controllable size and shape. These multivalent constructs also present the ability of disassemble under specific physiological conditions and of linking covalently to agent(s) such as a drug and/or imaging probes and/or targeting moiety so that they can be used as carries in biomedical applications.