Toxicity and t₂-weighted magnetic resonance imaging potentials of holmium oxide nanoparticles

In recent years, paramagnetic nanoparticles (NPs) have been widely used for magnetic resonance imaging (MRI). This paper reports the fabrication and toxicity evaluation of polyethylene glycol (PEG)-functionalized holmium oxide (Ho₂O₃) NPs for potential T₂-weighted MRI applications. Various characterization techniques were used to examine the morphology, structure and chemical properties of the prepared PEG–Ho₂O₃ NPs. MRI relaxivity measurements revealed that PEG–Ho₂O₃ NPs could generate a strong negative contrast in T₂-weighted MRI. The pilot cytotoxicity experiments showed that the prepared PEG–Ho₂O₃ NPs are biocompatible at concentrations less than 16 µg/mL. Overall, the prepared PEG–Ho₂O₃ NPs have potential applications for T₂-weighted MRI imaging.