Nanogel star polymers are developed as a new route for the formation of dual-mode nanoparticle systems for applications in the areas of synergistic therapeutic delivery, imaged therapeutic delivery, and dual-mode bioimaging agents. These extremely uniform, structurally versatile, water-soluble, unimolecular organic nanoparticles with tunable polyvalency and functionality are preprogrammed to upload different types of complex functional macromolecules spontaneously.