Ultrastable AgBiS2 Hollow Nanospheres with Cancer Cell-Specific Cytotoxicity for Multimodal Tumor Therapy

Specific cytotoxicity for catalytic nanomedicine triggered by the tumor microenvironment (TME) has attracted increasing interest. In this work, we prepared AgBiS₂ hollow nanospheres with narrow bandgaps via rapid precipitation in a weakly polar solvent, which lowered the intrinsic energy gap for the active production of highly reactive hydroxyl radicals (^•OH), especially in the TME. The as-prepared AgBiS₂ hollow nanospheres exhibited enhanced optical absorption and high photothermal conversion efficiency (44.2%). In addition, the hollow structured AgBiS₂ nanospheres were found to have a peroxidase-mimicking feature to induce cancer cell-specific cytotoxicity while exhibiting negligible cytotoxicity toward normal cells, which might be attributed to the efficient production of highly reactive ^•OH originating from the overexpression H₂O₂ in the TME caused by surface catalysis. In particular, the cancer cell-specific cytotoxicity of the nanospheres was greatly enhanced both in vitro and in vivo upon irradiation with a near-infrared (NIR) laser (808 nm). The above-mentioned features of the hollow structured AgBiS₂ will make it a promising candidate for tumor therapy.