NIR-driven intracellular photocatalytic oxygen-supply on metallic molybdenum carbide@N-carbon for hypoxic tumor...

The intracellular O₂-supply not only can relieve tumor hypoxia but also enhance the effects of photodynamic therapy (PDT). In this work, metallic Mo₂C@N-carbon@PEG nanoparticles were constructed to reveal the near infrared (NIR)-photocatalytic O₂ generation and promote photodynamic therapy (PDT). Here, (NH₄)₆Mo₇O₂₄·4H₂O nanorods and urea were adopted as resources that were calcined to obtain Mo₂C@N-carbon nanoparticles (20 nm). All samples displayed high NIR absorption as well as photothermal conversion efficiency of up to 52.7 % (Mo₂C@N-Carbon-3@PEG). The density functional theory calculations demonstrated the metallic characteristic of Mo₂C and that the consecutive interband/intraband charge-transition was responsible for the high NIR harvest and redox ability of electron-hole pairs, making the NIR-photocatalytic O₂ and reactive oxygen species (ROS) generation. In comparison with the pure Mo₂C, the heterostructure displayed twice the performance due to the enhanced charge-segregation between Mo₂C and N-carbon. Given the high X-ray absorption coefficient and photothermal ability, the nanocomposite could be used in novel computer tomography and photothermal imaging contrast. Furthermore, the novel biodegradation and metabolism behaviors of nanocomposites were investigated, which were reflected as elimination from the body (mouse) via feces and urine within 14 days. The as-synthesized Mo₂C@N-Carbon@PEG nanocomposites integrated the dual-model imaging, intracellular O₂-supply, and phototherapy into one nanoplatform, revealing its potential for anti-cancer therapy.