Silver nanoparticles can be used as antibacterial agents, e.g., in clothing or wound dressings. Copper nanoparticles have similar properties and are much cheaper. However, they tend to oxidize in air, which severely limits their applications. There is a need for simple, low-cost approaches to stabilize copper nanoparticles and protect them against oxidation.

Fu Tang, Lidong Li, University of Science and Technology Beijing, China, and colleagues have developed a synthesis of copper nanoparticles with improved oxidative stability. The team first oxidized corn starch using periodate. This modified starch was used as a reducing agent. Biocompatible polyethylenimine was used as a stabilizer. Both were combined with a copper sulfate solution to prepare the copper nanoparticles, which were isolated by centrifugation.

The synthesized nanoparticles are stable in air for over six months without oxidation. The researchers attribute this effect to strong interactions between the polyethylenimine and the copper, which block access to the nanoparticle surface. The team embedded the nanoparticles in an agar film and tested the film’s antibacterial properties using Escherichia coli bacteria. They found that the film effectively killed the bacteria. This demonstrates the promise of stabilized copper nanoparticles for medical applications.

• Mild Synthesis of Copper Nanoparticles with Enhanced Oxidative Stability and Their Application in Antibacterial Films,
  Liangzhen Tang, Li Zhu, Fu Tang, Chuang Yao, Jie Wang, Lidong Li,
  Langmuir 2018.
  https://doi.org/10.1021/acs.langmuir.8b02470