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Preparation, characterization, and utilization of multi-functional magnetic-fluorescent composites for bio-imaging and magnetic hyperthermia therapy

Rittikulsittichai, Supparesk, Singhana, Burapol, Bryan, William W., Sarangi, Subhasis, Jamison, Andrew C., Brazdeikis, Audrius, Lee, T. Randall
RSC advances 2013 v.3 no.21 pp. 7838-7849
aqueous solutions, encapsulation, fever, fluorescein, fluorescence, fluorescence emission spectroscopy, image analysis, magnetic properties, magnetism, nanocomposites, nanoparticles, pH, rhodamines, scanning electron microscopy, silica, therapeutics, transmission electron microscopy, umbelliferones
This paper describes the synthesis, characterization, and utilization of unique multi-functional magnetic composites that integrate optical and magnetic properties in a single structure for use in hyperthermia therapy, and magnetic and fluorescence imaging. The composites are comprised of nanoscale magnetic core particles that are encapsulated by a silica layer that contains covalently-embedded organic dyes. The morphologies of the nanocomposite particles were characterized by TEM and FE-SEM. Their optical and magnetic properties were evaluated by spectrofluorometry and SQUID magnetometry, respectively. The results demonstrate that the nanocomposites are monodisperse and uniformly spherical with well-defined shell–core structures; moreover, they exhibit high magnetic saturation, produce vivid fluorescence, and can be designed to provide exceptional stability in aqueous solution over a wide range of pH and at elevated temperatures. For the three dyes utilized in the synthesis of these composites, rhodamine B (RhB), fluorescein (Flu), and 7-hydroxycoumarin (Cou), the observed relative stability for the nanoparticles was: RhB-SiO₂–Fe₃O₄ > Flu-SiO₂–Fe₃O₄ > Cou-SiO₂–Fe₃O₄. Additionally, potential uses of these composite nanoparticles as bimodal contrast agents and therapeutic entities are demonstrated.