The Effect of Storage Conditions and Time on the Antimicrobial Activities of CuO Nanoparticles

In recent years, metal and metal oxide, especially copper oxide nanoparticles, have attracted a lot of attention due to their high antimicrobial activity and low-cost advantage, but there are few studies on how storage conditions and time change their effect after the particles are produced. In this study, CuO nanoparticles produced by the sol–gel method and an annealing temperature of 300 °C were left in an oxygenated natural environment. Their antimicrobial effects were determined at 3-month intervals for approximately 36 months using Escherichia coli . In addition, the antimicrobial behavior of CuO particles produced at different annealing temperatures (150-900 °C) under the same storage conditions was compared. CuO nanoparticle formation was visualized by FESEM and TEM, confirmed by single-phase monoclinic XRD spectra, and characterized by FTIR techniques. It was observed that the antimicrobial effect of CuO nanoparticles prepared at the 300 °C annealing temperature and released into the natural oxygen environment decreased by approximately 60 % after 36 months. The antimicrobial effect of other CuO particles in oxygen is similar for about 3 years, approximately 10 % at 150 °C and 20 % at 450 °C, but no decrease was observed for samples prepared at 600 °C annealing temperature. CuO nanoparticles are used in many fields such as health, cosmetic, paint and textile industries due to their antibacterial properties. It is very important to know how long CuO nanoparticles can maintain these antibacterial characteristics. For these reasons, in all these application areas, production with an annealing temperature of 600 °C is recommended to maintain the long-term antibacterial effect of CuO nanoparticles.