FeSe₂‐Decorated Bi₂Se₃ Nanosheets Fabricated via Cation Exchange for Chelator‐Free ⁶⁴Cu‐Labeling and Multimodal Image‐Guided Photothermal‐Radiation Therapy

Abstract

Multifunctional theranostic agents have become rather attractive to realize image-guided combination cancer therapy. Herein, we develop a novel method to synthesize Bi₂Se₃ nanosheets decorated with mono-dispersed FeSe₂ nanoparticles (FeSe₂/Bi₂Se₃) for tetra-modal image-guided combined photothermal & radiation tumor therapy. Interestingly, upon addition of Bi(NO₃)₃, pre-made FeSe₂ nanoparticles via cation exchange would be gradually converted into Bi₂Se₃ nanosheets, on which remaining FeSe₂ nanoparticles are decorated. The yielded FeSe₂/Bi₂Se₃ composite-nanostructures were then modified with polyethylene glycol (PEG). Taking advantages of the high r₂ relaxivity of FeSe₂, the X-ray attenuation ability of Bi₂Se₃, the strong near-infrared (NIR) optical absorbance of the whole nanostructure, as well as the chelate-free radiolabeling of ⁶⁴Cu on FeSe₂/Bi₂Se₃-PEG, <i>in vivo</i> magnetic resonance (MR)/computer tomography (CT)/photoacoustic (PA)/position emission tomography (PET) multimodal imaging was carried out, revealing efficient tumor homing of FeSe₂/Bi₂Se₃-PEG after intravenous injection. Utilizing the intrinsic physical properties of FeSe₂/Bi₂Se₃-PEG, <i>in vivo</i> photothermal & radiation therapy to achieve synergistic tumor destruction was then realized, without causing obvious toxicity to the treated animals. Our work presents a unique method to synthesize composite-nanostructures with highly integrated functionalities, promising not only for nano-biomedicine, but also potentially for other different nanotechnology fields.