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

Abstract 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.