  Research into developing dual modality probes enabled for magnetic resonance
imaging (MRI) and positron emission tomography (PET) has been on the rise
recently due to the potential to combine the high resolution of MRI and the
high sensitivity of PET. Current synthesis techniques for developing multimodal
probes is largely hindered in part by prolonged reaction times during
radioisotope incorporation - leading to a weakening of the radioactivity. Along
with a time-efficient synthesis, the resulting products must fit within a
critical size range (between 20-100nm) to increase blood retention time. In
this work, we describe a novel, rapid, microwave-based synthesis technique to
grow dextran-coated iron oxide nanoparticles doped with copper (DIO/Cu).
Traditional methods for coprecipitation of dextran-coated iron oxide
nanoparticles require refluxing for 2 hours and result in approximately 50 nm
diameter particles. We demonstrate that microwave synthesis can produce 50 nm
nanoparticles with 5 minutes of heating. We discuss the various parameters used
in the microwave synthesis protocol to vary the size distribution of DIO/Cu,
and demonstrate the successful incorporation of 64Cu into these particles with
the aim of future use for dual-mode MR/PET imaging.
