Metal and metal-oxide nanoparticles have received considerable interest in antimicrobial applications owing to their promise in treating drug-resistant bacterial infections. It is the oxidative stress induced by reactive oxygen species (ROS) that plays the essential role in enabling the antimicrobial capability of these nanoparticles. However, the low concentration of oxygen in an anaerobic environment prevents the formation of ROS, reducing the antimicrobial activity of most metal and metal-oxide nanoparticles against anaerobic bacteria. Calcium peroxide (CaO₂), which can effectively generate hydrogen peroxide (H₂O₂) in the absence of oxygen, offers a potential solution to this issue. To prepare uniform CaO₂ nanoparticles with controllable sizes is still an unmet challenge.

Dr. Shen reported a new approach to the facile synthesis of CaO₂ nanocrystals and their spherical aggregates with uniform, controllable sizes. The CaO₂ nanoparticles were synthesized using ethanol as solvent in the presence of poly(vinyl pyrrolidone) (PVP), which was used as a colloidal stabilizer. The nanoparticles were formed by the aggregation of CaO₂ primary nanocrystals (2–15 nm). The size of the spherical aggregates could be controlled in the range of 15–100 nm by simply varying the concentrations of CaCl₂ and/or PVP. Owing to the special capability to generate H₂O₂ in water, the CaO₂ nanocrystals and their spherical aggregates are promising for various local bio-applications, such as root canal filling, tooth whitening, and anti-bacterial infection (especially, for anaerobic infection). The research was published on Small (IF: 10.8) recently with title “Synthesis of CaO2 Nanocrystals and Their Spherical Aggregates with Uniform Sizes for Use as a Biodegradable Bacteriostatic Agent”.