Magneto-luminescent yttrium aluminum silicate-coated Fe3O4 nanocomposites for multimodal imaging, Cancer Theranostics, and antibacterial applications

Tm-doped Fe3O4@YAS core@shell nanocomposites were synthesized via a modified Stober method to integrate magnetic, luminescent, and biomedical properties. XRD and HR-TEM confirmed the cubic Fe3O4 core and amorphous YAS shell, with Tm incorporation enhancing morphological uniformity. The nanocomposites retained superparamagnetic behavior with saturation magnetization values suitable for MRI contrast and magnetic guidance. Photoluminescence spectra showed strong blue emission at 458 nm (1D2 -> 3F4) with optimal intensity at 2 wt% Tm, decreasing at higher concentrations due to dipole-dipole quenching. Biological assays revealed selective cytotoxicity toward MDA-MB-231 breast cancer cells, negligible toxicity to HUVECs, and enhanced antibacterial activity against S. aureus and E. coli. RT-qPCR indicated significant downregulation of IL-1 beta, IL-6, TNF-alpha, and COX-2 in cancer cells. These multifunctional properties highlight the potential of Tm-doped Fe3O4@YAS nanocomposites for integrated cancer imaging, magnetic guidance, optical tracking, and localized therapy.