FeS2@C-ICG-PEG nanostructure with intracellular O2 generation for enhanced photo-dynamic/thermal therapy and imaging

Here, photodynamic therapy (PDT), photothermal therapy (PTT) and multimode imaging have been integrated in to one-nanoplatform. The FeS2@C-PEG yolk-shell nanostructures (200 nm) have been synthesized, which possesses strong NIR absorption and high photothermal conversion (42.3%), ascribing to the narrow band gap and the novel hollow structure. Moreover, FeS2@C-PEG also reveals the NIR-triggered ROS (OH and O2–) generation, and the mechanism was investigated in detail, showing that the photo-excited electrons and dissolved O2 determine the ROS generation. Moreover, by evaluating the energy band of FeS2, the VB potential is enough to oxidize water to form O2 under NIR irradiation that relieves tumor hypoxia and enhances PDT. Besides, the Fenton reaction of Fe ion also makes FeS2 would degrade intracellular H2O2 to produce ·OH and O2 to assist PDT. To make the best of the hollow structure, photosensitizer ICG was loaded to further improve the PTT and PDT. Furthermore, FeS2@C-PEG possess high relaxivity (424.9 mM−1 s−1), making the potential contrast agent for MRI. And the synergistic effect of PTT and PDT further insures the enhanced anticancer efficacy.