Biosynthetic Ag₂S Nanoparticles for Photoacoustic Imaging-Guided Photothermal Therapy

Photothermal therapy (PTT) is acknowledged as a promising approach to tumor treatment. However, the synthesis process of PTT agents usually uses physical or chemical methods with a series of complex steps involving environmentally unfriendly solvents. This study presents an innovative method that employs genetically modified bacteria to produce size-controllable Ag₂S nanoparticles (30-80 nm) under moderate and eco-friendly conditions. The resulting Ag₂S nanoparticles can serve as theranostic agents for photoacoustic imaging (PAI) and PTT. In vitro and in vivo assays reveal that biosynthesized Ag₂S nanoparticles possess superior biocompatibility, stability, and minimal toxicity. Furthermore, the Ag₂S nanoparticles demonstrate exceptional PA imaging performance and a remarkable photothermal conversion efficiency of 38.51% at 808 nm near-infrared laser, achieving efficient antitumor efficacy. The biosynthesized Ag₂S nanoparticles offer advantages over traditional PTT agents, including high photothermal conversion efficiency, low toxicity, and high biocompatibility. Moreover, they can be used for both imaging and treatment, showing their great translational potential in future clinical applications. In conclusion, our research establishes a foundation for the biosynthesis of Ag₂S nanoparticles, providing a potential PTT agent for cancer diagnosis and treatment applications.