Color-tunable magnetic and luminescent hybrid nanoparticles: Synthesis, optical and magnetic properties

► Color-tunable magnetic and luminescent hybrid nanoparticles are synthesized in a simple and effective method. ► Hybrid nanoparticles remain the optical properties from QDs, displaying multicolor under UV excitation. ► Hybrid nanoparticles inherit the superparamagnetic properties originated from Fe3O4. ► Polyethyleneimine is used to avoid aggregation, attach QDs and transfer the surface properties of QDs from hydrophobic to hydrophilic.