Antioxidant nanoparticles could treat sepsis

Sepsis occurs when the body’s immune response to an infection spirals out of control. The inflammatory signals designed to kill bacteria and other invaders spread beyond the infection site and in the worst cases lead to organ failure and death. The only effective treatment for sepsis is antibiotics, but they target only the source of the infection, not its symptoms. To combat that inflammation, scientists at Seoul National University, led by Seung-Hoon Lee and Taeghwan Hyeon, synthesized ceria-zirconia nanoparticles to scavenge reactive oxygen species (ROS) that damage and kill cells. The cerium ion Ce3+ mimics natural catalysts that remove superoxide and hydroxyl radicals, so a high Ce3+:Ce4+ ratio in the particles is important for treating inflammation. Shifting to the +3 oxidation state is energetically unfavorable, however, so the researchers added Zr4+ ions to the nanoparticles to stabilize the Ce3+:Ce4+ ratio and improve their antioxidant capabilities over ceria-only nanoparticles (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201704904). The team tested the ceria-zirconia nanoparticles in cell and animal models of inflammation and sepsis and discovered that the nanoparticles targeted inflammation, reduced ROS, and prolonged the survival of mice with sepsis with only a single, low dose. The authors note that the nanoparticles “have the potential as a therapeutic nanomedicine for treating ROS-related inflammatory diseases.”