Z-scheme MoS/CoS@PEG nanoflowers: Intracellular NIR-II photocatalytic O production facilitating hypoxic tumor therapy.

Intratumoral hypoxia, which is in favour of cancer cell proliferation, invasion and metastasis, also inhibits photodynamic therapy (PDT) badly. Herein, second near-infrared (NIR-II) photocatalytic O production is established to realize hypoxia relief. MoS/CoS@PEG (MSCs@PEG) nanoflowers (100-150 nm) are prepared via a two-step hydrothermal method. These samples possess high NIR-II harvest and photothermal conversion (39.8 %, 1064 nm) ability. That not only reveals photothermal therapy (PTT) but also lifts the thermal energy of nanomaterials to replenish extra energy, making sure the co-excitation of MoS (1.14 eV) and CoS (1.40 eV) by low-energy NIR-II (1064 nm, 1.16 eV) laser. The investigation of band structure further displays the Z-Scheme characterization of MSCs heterostructure. These photo-excited holes/electrons hold great redox ability to form O (water splitting) and reactive oxygen species (ROS), simultaneously. In addition, MSC-2@PEG can be served to mimic catalase, peroxidase, and glutathione (GSH) oxidase to further boost oxidative stress. It is noted that heterostructure discovers the greater nanozyme activity, attributing to the lower resistance for charge transfer. Moreover, MSC-2@PEG displays a novel biodegradation ability to induce the elimination via urine and faeces within 14 days. Given the superparamagnetic and photothermal effect, the nanocomposite can be used as magnetic resonance and photothermal imaging (MRI and PTI) contrast. Associated with dual-imaging, intracellular O supplementation, and synergistic chemotherapy (CDT)/PTT/PDT, MSC-2@PEG possess great tumor inhibition that also efficiently motivates immune response for anticancer.