A Versatile Bi₂S₃/MnO₂ Based Nano-theranostic Agent for Triple-modal Imaging Guided Photothermal/Photodynamic Synergistic Therapy

Versatile nano-theranostic agents are highly desirable for the precision nanomedicine of tumors in recent years. In this work, a multifunctional diagnostic and therapeutic agent Bi₂S₃-MnO₂@BSA-Ce6 (BMBC) was successfully prepared by a combination strategy of facile chemical coupling and biomineralization under mild conditions. These BMBC nanoparticles with an average diameter of 17.6 ± 4.6 nm exhibited favorable physiological stability and negligible toxicity. This agent expressed outstanding performance of photothermal conversion (η = 45.8%) under 808 nm laser radiation and generation of ¹O₂ under 650 nm laser irradiation. Due to the strong X-ray attenuation performance of element Bi and the highly effective magnetic moment of Mn²⁺, this agent exhibited favorable performance of X-ray computed tomography (CT) imaging (35.60 HU•mL•mg⁻¹) and magnetic resonance (MR) imaging (r1 = 5.22 mM⁻¹•s⁻¹) in vitro. Furthermore, most of the HeLa cells treated with BMBC NPs were dead in the MTT and Calcein-AM/PI staining experiments, demonstrating the excellent effect of intracellular synergistic therapy. Overall, this theranostic agent could serve as a promising nano-platform for photothermal/photodynamic synergistic therapy of tumors under the guidance of infrared thermal (IRT)/MR/CT imaging.