Synthesis and Modification of Selected Rare Earth Nanoparticles

The goal of this research is to develop multifunctional nanomaterials for biological applications. The rare earth based nanoparticles (RENPs) have a potential to offer multiple modalities, which can be utilized in more comprehensive imaging of biological tissues. The specific goal was to modify the RENPs with clusters of transition metals in order to enhance their luminescence signal. The luminescent system based on the Er$^{3+}$:Y$_{2}$O$_{3}$ nanoparticles (NPs) was selected for the present studies. Several synthetic approaches were investigated in order to control the size and shape. The precipitation from homogenous solution using the urea decomposition yielded perfectly spherical Er$^{3+}$:Y$_{2}$O$_{3}$ with narrow size distribution and particle diameter of approximately 250 nm. The synthesis of Er$^{3+}$:Y$_{2}$O$_{3}$ using the microemulsion precipitation resulted in the irregularly shaped NPs with the average diameter of approximately 100 nm. The Er$^{3+}$:Y$_{2}$O$_{3}$ NPs surrounded by chitosan shell were modified with gold clusters in order to enhance their luminescence by metallic surface plasmon resonance. The luminescence of such [Er$^{3+}$:Y$_{2}$O$_{3}$][Chitosan-Au] hybrid NPs was investigated as a function of the gold content in the chitosan shell.