Biomedical Applications of Lanthanide Oxide Nanoparticles

Lanthanide (Ln) oxide nanoparticles (NPs) have potential applications in various biomedical areas such as magnetic resonance imaging (MRI), X-ray computed tomography (CT), fluorescence imaging (FI), and gadolinium neutron-capture therapy (GdNCT). Ln oxide NPs are extremely useful for the diagnosis and treatment of conditions such as tumors. For in vivo applications, NPs should have an ultra-small particle diameter to allow their excretion from the body through the renal system after intravenous administration. Ln oxide NPs are suitable in this respect because they have excellent imaging properties at ultrasmall particle diameters. They are paramagnetic and show appreciable magnetization at room temperature. This property makes them suitable MRI contrast agents. Ln oxide NPs can be used as FI agents as they show various absorption and emission properties in the visible and near infrared (NIR) regions. Moreover, they show high X-ray attenuation properties, making them suitable CT contrast agents. Gd has the highest thermal neutroncapture cross section among stable radioisotopes, making it an effective neuron-capture therapy agent. By utilizing a combination of their enumerated properties, mixed or doped Ln oxide NPs could be used for multimodal imaging techniques as well as theragnosis of tumors.