Hybrid Magnetic Nanoparticles and Quantum Dots Stabilized by Polyhydroxylated Polyesters for Biolabeling and Magnetic Resonance Imaging

Magnetic particles (MPs) and quantum dots (QDs) are highly attractive for biomedical imaging, yet their broader application is often limited by poor aqueous dispersibility and instability. Here, we report a simple, robust, and versatile polymer coating strategy based on an apple-grape-enriched polymer system that enables the efficient phase transfer of hydrophobic Fe 2 O 3 MPs, CdSe@ZnS QDs, and their hybrid nanocomposites (magnetic quantum dots, MQDs) into water, while preserving their intrinsic properties. The resulting nanoparticles exhibit excellent colloidal stability and retain strong magnetic and fluorescent performance. The polymer-coated MPs demonstrate effective magnetic resonance imaging (MRI) contrast capability, whereas the QDs enable efficient labeling of live cancer cells. Notably, the bifunctional MQDs integrate both imaging modalities within a single platform. This approach provides a facile route to high-quality, water-dispersible nanomaterials, offering significant potential for next-generation bimodal imaging, particularly for T 1 -weighted MRI and fluorescence-guided bioimaging applications.