Superior CdSe/ZnS@Fe ₂ O ₃ Yolk‐Shell Nanoparticles as Optically Active MRI Contrast Agents**

We have developed a robust synthesis methodology for quantum dots (QDs) nanoparticles with magnetic properties designed biomodal imaging. These nanocrsytlas consists of semiconductor dot core engineered fluorescence, which is located in paramagnetic iron oxide shell that acts as resonance imaging (MRI) contrast agent. Yolk-shell CdSe/ZnS@Fe2O3 (NPs) are synthesized via sonochemical decomposition pentacarbonyl (Fe(CO)5) using the oleylamine (OAm) ligand. The method fluorescent NPs can be used MRI agents provided advantages such improved efficiency and homogeneous size distributions. It has been determined luminescence decreases coatings made at high temperatures by thermal decomposition. In order to eliminate disadvantage elevated temperatures, method, allows coating low used. With this yolk-shell (CdSe/ZnS@Fe2O3) were produced photoluminescence optimized was injection temperature Fe(CO)5 60 ° C, Fe(CO)5/CdSe@ZnS ratio 0.7, OAm/Fe(CO)5 volume 1.43 an oxidation time 5 min. Under these conditions, found 78 %, nanoparticle sizes between 11–14 nm r1 value 0.199, r2 0.518 analysis. optically active positive (T1 weighted) predicted pave way future advanced bio-imaging systems.