Physicochemical and Multimodal Imaging Properties of Core–Shell Ln₂O₃@Carbon Nanoparticles (Ln = Tb and Ho)

In this study, core–shell Ln₂O₃@carbon nanoparticles (core = Ln₂O₃ and shell = carbon; Ln = Tb and Ho) were synthesized for the first time by preparing Ln₂O₃ nanoparticles through a polyol method, followed by carbon coating using D-glucose as a carbon precursor in aqueous media. The synthesized Ln₂O₃@carbon nanoparticles exhibited good colloidal stability in solution and very low toxicity in in vitro cellular cytotoxicity tests. They exhibited paramagnetic magnetization values that increased with increasing applied field strength, resulting from spin–orbit magnetic moments of 4f-electrons; hence, they yielded negligible r₁ (<0.1 s⁻¹mM⁻¹) and appreciable r₂ values (3.446 and 3.677 s⁻¹mM⁻¹ for Ln = Tb and Ho, respectively) at 3 T, highlighting their potential as T₂ MRI contrast agents, particularly at high MR fields. In addition, the carbon coating shell exhibited photoluminescence at 460 nm, suitable for applications in fluorescence imaging probes.