Multimodal Magnetic Nanoparticle-Quantum Dot Composites

Multimodal nanocomposites that combine optical and magnetic functionalities are of great interest for applications such as imaging and temperature sensing. Ternary CuInS₂ (CIS)-based quantum dots (QDs) offer low toxicity, strong near-infrared (NIR) emission, and high photostability, making them promising for optical nanothermometry and imaging. In this study, CIS QDs were synthesized using an aqueous cysteine-mediated approach. Manganese ferrite (MnFe₂O₄) nanoparticles were prepared as the magnetic component due to their non-toxicity and superparamagnetic properties. To integrate both functionalities, QDs and magnetic nanoparticles (MNPs) were encapsulated in silica and then combined to form multimodal CIS/MnFe₂O₄/SiO₂ nanocomposites. The structure and morphology of the materials were characterized by TEM and XRD, while their optical properties were examined using UV-Vis, photoluminescence (PL) spectroscopy. This design ensured optical isolation, preventing fluorescence quenching while maintaining colloidal stability. The obtained composites exhibited PL in the NIR region and a thermosensitivity of 2.04%/°C. TEM analysis confirmed uniform silica shell formation and successful integration of both components within the composite. The materials also retained the superparamagnetic behavior of MnFe₂O₄, making them suitable for combined optical and magnetic functionalities. These results demonstrate the potential of CIS/MnFe₂O₄/SiO₂ nanocomposites as multifunctional platforms for optical imaging, temperature monitoring, and magnetically modulated effects.