In this study, the preparation of a new kind of magnetic and luminescent Fe₃O₄/CdSe/CdS nanocomposites was demonstrated. Superparamagnetic Fe₃O₄ nanoparticles were first synthesized by hydrothermal coprecipitation of ferric and ferrous ions, followed by the modification of their surfaces with L-aspartic acid. The surface-modified Fe₃O₄ nanoparticles were then linked to CdSe/CdS quantum dots (QDs), which were modified with mercaptoacetic acid, to form the Fe₃O₄/CdSe/CdS fluorescent magnetic nanocomposites through the coordination of the amino groups on the surfaces of Fe₃O₄ and the carboxyl groups on CdSe/CdS QDs in the presence of 1-ethyl-3-(3-dimethylaaminopropyl) carbodilnide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS). The structure and properties of as-synthesized nanocomposites were characterized by XRD, EDS, TEM, Vibrating sample magnetometer (VSM) and photoluminescence (PL). It was indicated that the nanocomposites have a typical diameter of 40 nm and possess not only magnetic properties but also photoluminescence properties. The synthesized bifunctional nanocomposites could be used in a variety of bioanalytical assays such as luminescence detection, magnetic separation, drug delivery, biotechnology/biomedicine and so on.

Key words: bifunctional nanostructures, quantum dots, magnetic nanoparticles