Sub-10 nm Fe₃O₄@Cu_2–<i>x</i>S Core–Shell Nanoparticles for Dual-Modal Imaging and Photothermal Therapy

TLDR

Photothermal nanomaterials are promising for imaging and therapy, yet creating small, thermally stable particles remains a major challenge. This study reports the rational design and synthesis of ultrasmall (<10 nm) Fe₃O₄@Cu₂₋ₓS core–shell nanoparticles that combine high photothermal stability with superparamagnetic properties. The photothermal response of the particles can be finely tuned by adjusting the Cu content in the core–shell structure. These nanoparticles serve as effective T₂‑weighted MRI and near‑infrared thermal imaging probes, and they achieve in vitro and in vivo photothermal ablation of cancer cells, demonstrating a synergistic magneto‑photothermal effect useful for multimodal biomedical probes.

Abstract

Photothermal nanomaterials have recently attracted significant research interest due to their potential applications in biological imaging and therapeutics. However, the development of small-sized photothermal nanomaterials with high thermal stability remains a formidable challenge. Here, we report the rational design and synthesis of ultrasmall (<10 nm) Fe3O4@Cu2-xS core-shell nanoparticles, which offer both high photothermal stability and superparamagnetic properties. Specifically, these core-shell nanoparticles have proven effective as probes for T2-weighted magnetic resonance imaging and infrared thermal imaging because of their strong absorption at the near-infrared region centered around 960 nm. Importantly, the photothermal effect of the nanoparticles can be precisely controlled by varying the Cu content in the core-shell structure. Furthermore, we demonstrate in vitro and in vivo photothermal ablation of cancer cells using these multifunctional nanoparticles. The results should provide improved understanding of synergistic effect resulting from the integration of magnetism with photothermal phenomenon, important for developing multimode nanoparticle probes for biomedical applications.