Development of Multifunctional Luminomagnetic Nanoparticles as Bioimaging Contrast Agents*

Trivalent rare earth doped nanocrystalline materials with multiple functionalities have drawn special attention in biomedical industry. Current research is focused on the use of various materials with dual functionality for potential multifunctional applications. In this project, we are developing near infrared(NIR) based nanocrystals (NCs) as contrast agents with multimodal features comprising of strong NIR fluorescence, X-ray fluorescence and magnetic properties by utilizing the superparamagnetic features of Gd$^{3+}$, the high X-ray excitation cross section of Lu$^{3+}$, and the NIR fluorescence of Nd$^{3+}$. Halides, such as MGdLuF$_{4}$ (M=K,Na), were doped with NIR active rare earth ions, Nd$^{3+}$, where synthesis conditions have been optimized to obtain the brightest phosphor with a size of sub-50 nm. Characterization of the NCs were performed to explore the excitation and emission properties, crystal structure, morphology, magnetization properties, and X-ray fluorescence properties. The potential use of these NCs can be utilized as contrast agents for medical imaging application such as optical imaging, magnetic resonance (MRI) and X-ray imaging.