NCCLS (2012) Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically. NCCLS Document M7-A9. Approved Standard. Seventh Edition, Which Describes Standard Broth Dilution (Macrodilution and Microdilution) and Agar Dilution Techniques for Measuring the in Vitro Susceptibility of Bacteria to Antimicrobial Agents.
AUTHORS: Matheus Vinicius de Oliveira Brisola Maciel, Aline da Rosa Almeida, Michelle Heck Machado, Ana Paula Zapelini de Melo, Cleonice Gonçalves da Rosa, Daniele Ziglia de Freitas, Carolina Montanheiro Noronha, Gerson Lopes Teixeira, Rafael Dutra de Armas, Pedro Luiz Manique Barreto
ABSTRACT: The present investigation details a green synthesis of silver nanoparticles (AgNP) using the essential oil of Syzygium aromaticum L. (clove) as reducing agent, which is a matrix with a high content of eugenol, an important compound for the reducing action of silver nitrate. The synthesis of AgNP was performed at different pH conditions (pH 7, 8, 9 and 10), and was monitored by UV-Vis Spectroscopy, Dynamic Light Scattering (DLS) and Transmission Electron Microscopy. The synthesized nanoparticles presented characteristic Surface Plasmon Resonance bands with maximum absorbance between 405 and 460 nm. The DLS analysis revealed particle sizes from 31 to 72 nm and zeta potential between -30.1 and -50.8 mV indicating good stability against the agglomeration of the particles in solution. The micrographs obtained by TEM showed different particle shapes and a predominance of spherical-shaped nanoparticles, and average size ranging from 27 to 94 nm. The clove-based silver nanoparticles were efficient in controlling the growth of Escherichia coli and Staphylococcus aureus bacteria, and the minimum inhibitory concentration ranged from 60 to 100 μL/mL. This study highlights the feasibility of clove essential oil as an alternative for the synthesis of silver nanoparticles by a simple, inexpensive and eco-friendly method.