title: Magnetic and optical properties of multifunctional core-shell radioluminescence nanoparticles.
abstract: When X-rays irradiate radioluminescence nanoparticles, they generate visible and near infrared light that can penetrate through centimeters of tissue. X-ray luminescence tomography (XLT) maps the location of these radioluminescent contrast agents at high resolution by scanning a narrow X-ray beam through the tissue sample and collecting the luminescence at every position. Adding magnetic functionality to these radioluminescent particles would enable them to be guided, oriented, and heated using external magnetic fields, while their location and spectrum could be imaged with XLT and complementary magnetic resonance imaging. In this work, multifunctional monodispersed magnetic radioluminescent nanoparticles were developed as potential drug delivery carriers and radioluminescence imaging agents. The particles consisted of a spindle-shaped magnetic γ-Fe2O3core and a radioluminescent europium-doped gadolinium oxide shell. Particles with solid iron oxide cores displayed saturation magnetizations consistent with their ~13% core volume, however, the iron oxide quenched their luminescence. In order to increase the luminescence, we partially etched the iron oxide core in oxalic acid while preserving the radioluminescent shell. The core size was controlled by the etching time which in turn affected the particles' luminescence and magnetic properties. Particles with intermediate core sizes displayed both strong magnetophoresis and luminescence properties. They also served as MRI contrast agents with relaxivities of up to 58 mM-1s-1(r2) and 120 mM-1s-1(r2*). These particles offer promising multimodal MRI/fluorescence/X-ray luminescence contrast agents. Our core-shell synthesis technique offers a flexible method to control particle size, shape, and composition for a wide range of biological applications of magnetic/luminescent nanoparticles.
authors: Department of Chemistry, Center for optical materials science and engineering (COMSET), and environmental toxicology program; Clemson University, Clemson, SC, 29634, USA.
authors: Hongyu
authors: H
authors: Chen
authors: Vanderbilt University Institute of Imaging Science (VUIIS), Department of Radiology and Radiological Sciences Vanderbilt University, Nashville, TN, 37232, USA.
authors: Daniel C
authors: DC
authors: Colvin
authors: School of Materials Science and Engineering, Clemson University, Clemson, SC, 29634, USA.
authors: Bin
authors: B
authors: Qi
authors: Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA.
authors: Thomas
authors: T
authors: Moore
authors: Department of Physics & Astronomy, Clemson University, Clemson, SC, 29634, USA.
authors: Jian
authors: J
authors: He
authors: School of Materials Science and Engineering, Clemson University, Clemson, SC, 29634, USA.
authors: O Thompson
authors: OT
authors: Mefford
authors: Department of Bioengineering, Clemson University, Clemson, SC, 29634, USA.
authors: Frank
authors: F
authors: Alexis
authors: Vanderbilt University Institute of Imaging Science (VUIIS), Department of Radiology and Radiological Sciences Vanderbilt University, Nashville, TN, 37232, USA.
authors: John C
authors: JC
authors: Gore
authors: Department of Chemistry, Center for optical materials science and engineering (COMSET), and environmental toxicology program; Clemson University, Clemson, SC, 29634, USA.
authors: Jeffrey N
authors: JN
authors: Anker