The synthesis of two-dimensional Bi2Te3@SiO2 core–shell nanosheets for fluorescence/photoacoustic/infrared (FL/PA/IR) tri-modal imaging-guided photothermal/photodynamic combination therapy

Abstract

Two-dimensional Bi₂Te₃ nanosheets (NSs) have recently been validated as a new type of photothermal agent to provide an alternative option for tumor ablation via light-induced hyperthermia. However, the surface of Bi₂Te₃ NSs lacks active radicals for the conjugation of functional molecules, which undoubtedly impedes their versatile utilization in medical areas. Here, the surface activation of Bi₂Te₃ NSs was accomplished via the in situ growth of an SiO₂ nanoshell assisted by tetraethyl orthosilicate (TEOS). Upon the co-condensation of (3-aminopropyl)triethoxysilane (ATPES), terminal amino groups (–NH₂) were generated on the surface of the Bi₂Te₃@SiO₂ NSs, which were further covalently coupled with the photosensitizer chlorin e6 (Ce6) through a standard amide reaction. The resultant Bi₂Te₃@SiO₂/Ce6 (BSC) NSs displayed admirable photothermal properties, a high Ce6 loading capacity, and good biocompatibility. Upon dual-wavelength laser irradiation, an excellent tumor suppression effect arising from thermal ablation and reactive oxygen species (ROS)-induced apoptosis was verified both in cell experiments and in animal studies. In addition, synchronous fluorescence/photoacoustic/infrared (FL/PA/IR) tri-modal imaging could provide useful information for both tumor diagnosis and prognosis. Overall, this facile strategy for the activation of Bi₂Te₃ is regarded to be universal for the development of more versatile Bi₂Te₃-based nanoplatforms, which should favor the rapid diagnosis and effective treatment of fatal diseases.