Core–multi-shell design: unlocking multimodal capabilities in lanthanide-based nanoparticles as upconverting, T 2 -weighted MRI and CT probes

Core/shell/shell nanoparticle design with a controlled inner NaGdF 4 layer between the upconverting Er/Yb-doped NaGdF 4 core and the magnetic NaDyF 4 shell suppressed Dy 3+ -induced emission loss, while simultaneously enhancing MRI T 2 and CT performance.