Abstract: Disclosed are novel, targeted, self-assembled nanoparticles radiolabeled with technetium-99m (Tc-99m) as radiodiagnostic compositions, methods of using these compositions and methods for preparing such radiolabeled compositions. Specifically, the compositions of the nanoparticles are composed of self-assembled polyelectrolyte biopolymers having targeting moieties, which can be suitable for targeted delivery of radionuclide metal ions complexed to the nanoparticles. These radiolabeled nanoparticles can specifically bind and internalize into the targeted tumor cells to realize the receptor mediated uptake. Radiolabeled, targeted nanoparticulate composition, methods for making, radiolabeling and using such compositions in the field of diagnosis and therapy are also provided.