Core-satellite nanoreactors based on cationic photosensitizer modified hollow CuS nanocage for ROS diffusion enhanced phototherapy of hypoxic tumor

Photodynamic therapy (PDT) efficiency is directly affected by the reactive oxygen species (ROS) generated by photosensitizers. However, ROSs' ultrashort life span and limited diffusion distance restrict the PDT efficiency. Therefore, it is important to control the delivery strategy of photosensitizers for PDT treatment. Herein, the core-satellite nanoreactors were fabricated with oxygen generation and ROS diffusion properties. The hollow CuS encapsulating horseradish peroxidase (HRP) was combined with the cationic photosensitizers (PEI-Ce6). The unique photosensitizers delivery strategy makes the nanoreactors achieve ROS diffusion-enhanced PDT effect. First, HRP in "core" (HRP@CuS) can decompose hydrogen peroxide (H2O2) to O2, increasing O2 levels on the surface of the nanoreactor. Second, the Ce6 molecules covalent-linked with PEI are uniformly dispersed on the surface of CuS as a "satellite", avoiding Ce6 aggregation and causing more Ce6 molecules be activated to produce more 1O2. Due to the Ce6 was on the surface of the CuS nanocages, the generated ROS may ensure a larger diffusion range. Meanwhile, the inherently CuS nanocages exhibit photothermal and photoacoustic (PA) effect. The photothermal effect further enhances the ROS diffusion. Under the guidance of PA imaging, nanoreactors exhibit highly efficient hypoxic tumor ablation via photodynamic and photothermal effect. Overall, the core-satellite nanoreactors provide an effective strategy for tumor therapy, further promoting the research of photosensitizers delivery.