Antimicrobial activity of ZnO and ZnFe2O4 nanoparticles obtained by a solvent-free method

B. Paz-Díaz, A. Vázquez-Olmos, A. Flores-Almaguer, R. Sato-Berrú, A.L. Fernández-Osorio
Instituto de Ciencias Aplicadas y Tecnología, UNAM,

Keywords: ZnO, ZnFe2O4, antimicrobial activity, Staphylococcus epidermidis, Pseudomonas aeruginosa, Minimum Inihibitory Concentration


The current therapeutic treatments for infectious diseases are highly ineffective, which causes millions of deaths around the world. The resistance to antibiotics has been developed by the microorganisms due to the lack of control in the production, distribution, prescription and disposal of the antimicrobial agents. The search for new compounds, as alternatives to eliminate a wide variety of infectious agents, is constant and necessary. Metal oxide nanoparticles have been a new proposal to fight against antibiotic resistance. The antimicrobial activity depends on their size and morphology and these characteristics are given by the synthesis method. This new alternative may impact the world health, and due to the necessity of eliminating the infectious agents, the synthesis methods used to fabricate the nanoparticles (NPs) should be low cost, easy and carried out in mild reaction conditions. This paper presents the mecanosynthesis, characterization, and evaluation of antimicrobial activity of ZnO NPs of 18nm and ZnFe2O4 NPs of 6nm, against 2 bacteria; Gram-positive Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa. The ZnO nanoparticles were synthesized from zinc acetate and NaOH, and the ZnFe2O4 from iron acetylacetonate, zinc acetate and NaOH. The reactants were ground together and the obtained product was washed and separated by centrifugation. Finally, the NPs were heated at 400ºC for 2 hours. The products were characterized by powder X-Ray diffraction (XRD), electronic paramagnetic resonance (EPR), UV-Vis, FTIR and Raman spectroscopies. Antibiograms were used to evaluate the antibacterial activity against the 2 bacteria and also the Minimum Inhibitory Concentration (MIC) was carried out for each system (ZnO and ZnFe2O4 NPs). The antibiogram pattern shows that the ZnO nanoparticles present antimicrobial activity against both tested bacteria. For the ZnFe2O4 nanoparticles, the pattern only shows activity against S. epidermidis. However, the MIC analysis shows that both nanoparticle systems show antimicrobial activity against both bacteria.