Zinc oxide nanoparticles synthesized by the polyol method: characterization and evaluation of the antibacterial activity

The use of nanostructured materials synthesized from metal salts has increasingly attracted the attention of researchers and industries to develop innovative applications in areas such as energy, health and food. Due to the antibacterial properties of silver, copper and zinc oxide, they are potential substituents to the traditional antibacterial agents, such as organochlorines and arsenic derivatives. Once zinc oxide is not classified as heavy meta, has low toxicity, and is biocompatible, it appears as an alternative material for applications in the medical area and water treatment. The main objective of this work was to synthesize zinc oxide nanoparticles by the polyol method and evaluate the antibacterial activity of these nanostructures against the Gram negative bacteria Escherichia coli. The syntheses were carried out in the presence and absence of poly(vinyl pyrrolidone) to investigate the influence of this stabilizing agent on the morphological properties of the nanoparticles. All of the samples were characterized by UV-Vis spectrophotometry, X-ray diffractometry, field emission scanning electron microscopy and transmission electron microscopy. Tests to evaluate the antibacterial activity of different amounts of the zinc oxide nanoparticles were performed according to the ASTM E-2149. The results obtained demonstrated that the polyol method was able to produce zinc oxide nanoparticles with high purity and average diameter around 20 nm, regardless the presence of poly( vinyl pyrrolidone). Microbiological assays showed that zinc oxide nanoparticles produced excellent antibacterial activity against the bacteria Escherichia coli when applied at concentrations higher than 50 mg.L-1.