The various embodiments herein provide for the engineered multimodal super paramagnetic iron oxide nanoparticles (SPIONs) with a fluorescent dye. The SPIONs comprise fluorescent polymer dye arranged in a gap between a SPION core and a gold shell. The SPIONS are provided with a gold coating. The gap is made up of a polymeric molecule such as 6-arm anthracene terminated. The core of the nanoparticle is made up of a magnetic metal oxide. The method for synthesizing SPIONs involves preparing carboxyl-dextran complex and the SPIONS. The SPIONs are coated with carboxyl-dextran complex. The coated SPIONs coated are subjected to fluorescent polymer and gold nano shell coating. The prepared SPIONs are characterized by light scattering measurement and magnetization measurements.
