Cu2−xSe/Bi2Se3@PEG Z-scheme heterostructure: a multimode bioimaging guided theranostic agent with enhanced photo/chemodynamic and photothermal therapy

Abstract

Photodynamic therapy (PDT) can be defined as a kind of intracellular photocatalysis. Inspired by the design of photocatalysts, the construction of the heterojunction also is expected to improve the production of reactive oxygen species (ROS) for PDT. Herein, the Cu_2−xSe/Bi₂Se₃@PEG (CB3@PEG) nano-heterostructure has been prepared by a cation-exchange process, where the interaction between the host and exchange agent is vital. CB3@PEG exhibits the near-infrared (NIR)-triggered hydroxyl radical and singlet oxygen (˙OH and ¹O₂) generation, which is more than 6 times in contrast with that of pure Cu_2−xSe@PEG, attributed to the Z-scheme charge transfer mechanism with the high redox ability and great charge separation. Moreover, with the narrower band gap of Bi₂Se₃, CB3@PEG exhibits enhanced NIR harvest as well as high photothermal conversion efficiency (60.4%). Due to the Fenton reaction caused by the Cu ion, CB3@PEG is endowed with the chemodynamic therapy (CDT) and signal-enhanced T₁-weight magnetic resonance imaging (MRI) capacity. In addition, the great photothermal ability and X-ray absorption coefficient provide outstanding contrast in photothermal imaging (PTI) and computerized tomography (CT) imaging. Finally, the multi-imaging combined with the synergistic treatment (PTT/CDT/PDT) makes CB3@PEG achieve enhanced efficiency in anticancer therapy.