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

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.