Tunable magnetic-luminescent Tb:SiO2@Fe3O4 nanoparticles for theranostic applications

Magnetic-luminescent Tb-doped SiO2@Fe3O4 core@shell nanoparticles were synthesized via a two-step approach and evaluated for biomedical applications. Photoluminescence (PL) analysis showed broad emissions from the SiO2 matrix and distinct Tb3+-related peaks at 543–621 nm, corresponding to 5D4-7Fj (j=5,4,3) transitions. Increasing Tb content led to enhanced PL intensity and crystallinity. Vibrating sample magnetometer (VSM) confirmed superparamagnetic behavior, with high saturation magnetization values—45.53 emu/g for 1% and 36.93 emu/g for 3 mol. % Tb-doped samples—exceeding values reported in prior studies. The inverse relationship between Tb concentration and magnetization is attributed to 3d–4f orbital interactions and enhanced magneto-crystalline anisotropy. These multifunctional nanoparticles, combining high magnetic responsiveness and optical traceability, demonstrate strong potential for use in non-invasive, image-guided therapies, marking a significant advancement in multifunctional nanomedicine