Cu nanocluster decorated Zn-Mn ferrite nanocomposites for dual-modal fluorescence and magnetic resonance imaging

Red-emissive Cu nanoclusters were synthesized via a green room-temperature strategy using glutathione and ascorbic acid. • Zn 0.4 Mn 0.6 Fe 2 O 4 nanoparticles were selected as the magnetic component owing to their superior magnetic properties over conventional Fe 3 O 4 . • Cu nanocluster-decorated Zn 0.4 Mn 0.6 Fe 2 O 4 nanocomposites were successfully fabricated through a simple assembly process. • The optimized nanocomposite integrated bright red fluorescence with excellent T 2 -weighted magnetic resonance performance. • A green and low-cost strategy was developed for constructing multifunctional fluorescence/MR nanocomposites. Given the intrinsic limitations of single-modality imaging, integrating optical and magnetic functionalities into a single nanoplatform offers a promising strategy for multimodal imaging. Herein, Cu nanocluster-decorated Zn 0.4 Mn 0.6 Fe 2 O 4 nanocomposites (CuNCs-ZMF) were rationally fabricated for dual-modal fluorescence and magnetic resonance imaging. Glutathione-protected CuNCs were synthesized using ascorbic acid as a mild reductant, while superparamagnetic Zn 0.4 Mn 0.6 Fe 2 O 4 nanoparticles were synthesized via thermal decomposition and subsequently surface-functionalized with cetyltrimethylammonium bromide to improve aqueous dispersibility and facilitate assembly with CuNCs. The resulting CuNCs-ZMF exhibited red fluorescence centered at 660 nm with an absolute quantum yield of 5.89% and a transverse relaxivity ( r 2 ) of 160.52 mM −1 s −1 . T 2 -weighted MR imaging demonstrated Fe concentration-dependent negative contrast enhancement, while in vivo imaging revealed pronounced darkening of the liver region following intravenous administration. CCK-8 assays further demonstrated relatively favorable cytocompatibility at low-to-moderate concentrations. These results demonstrate the successful integration of fluorescence and magnetic resonance imaging capabilities and support the potential of CuNCs-ZMF for fluorescence/MRI dual-modal imaging applications.