Yb/Er-doped Fe3O4@ZnO core@shell nanocomposites as multifunctional nanoplatforms for biomedical applications

Abstract

Fe3O4@ZnO and Yb/Er-doped Fe3O4@ZnO core@shell nanocomposites were rationally synthesized via a co- precipitation and modified St¨ ober route to achieve multifunctional performance for biomedical applications. Structural and morphological analyses confirmed crystalline Fe3O4 cores and ZnO shells, while lanthanide incorporation induced lattice expansion and enhanced agglomeration. Magnetic measurements revealed soft superparamagnetic-like behavior with suppressed coercivity and remanence, and the Fe3O4@4Yb5Er:ZnO composition exhibited increased magnetization due to the additive paramagnetic contribution of Yb3 +/Er3+ ions. Optical studies demonstrated efficient Yb3+→Er3+energy transfer under 980 nm excitation, generating bright green and red upconversion luminescence suitable for bioimaging. Antibacterial assays showed selective inhibition of Staphylococcus aureus, whereas Escherichia coli exhibited lower susceptibility. Cytocompatibility and gene expression analyses indicated that Fe3O4@4Yb5Er:ZnO promotes endothelial migration, angiogenic signaling, and extracellular matrix remodeling. Overall, these findings demonstrate that controlled lanthanide doping enables the integration of tunable magnetic, optical, antibacterial, and pro-angiogenic functionalities within a single nanosystem, underscoring their potential for theranostic and regenerative medicine applications.