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, a novel method is developed to synthesize Bi 2 Se 3 nanosheets decorated with mono‐dispersed FeSe 2 nanoparticles (FeSe 2 /Bi 2 Se 3 ) for tetra‐modal image‐guided combined photothermal and radiation tumor therapy. Interestingly, upon addition of Bi(NO 3 ) 3 , pre‐made FeSe 2 nanoparticles via cation exchange would be gradually converted into Bi 2 Se 3 nanosheets, on which remaining FeSe 2 nanoparticles are decorated. The yielded FeSe 2 /Bi 2 Se 3 composite‐nanostructures are then modified with polyethylene glycol (PEG). Taking advantages of the high r 2 relaxivity of FeSe 2 , the X‐ray attenuation ability of Bi 2 Se 3 , the strong near‐infrared optical absorbance of the whole nanostructure, as well as the chelate‐free radiolabeling of 64 Cu on FeSe 2 /Bi 2 Se 3 ‐PEG, in vivo magnetic resonance/computer tomography/photoacoustic/position emission tomography multimodal imaging is carried out, revealing efficient tumor homing of FeSe 2 /Bi 2 Se 3 ‐PEG after intravenous injection. Utilizing the intrinsic physical properties of FeSe 2 /Bi 2 Se 3 ‐PEG, in vivo photothermal and radiation therapy to achieve synergistic tumor destruction is then realized, without causing obvious toxicity to the treated animals. This 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.