Study on antibacterial mechanism of Mg(OH)2 nanoparticles

Recently, Mg(OH)2 nanoparticles were reported to be efficient antibacterial agent. In this work, the antibacterial behavior of Mg(OH)2 nanoparticles against Escherichia coli was further investigated. Results indicate that the antibacterial mechanism of Mg(OH)2 nanoparticles is different from the existing ones of metal-based compounds. It is found that the Mg2+ increased a lot in the sample culture after the antibacterial test. Mg(OH)2 nanobars of about 2 μm length did not show any antibacterial property, and the ultraviolet illumination for certain time can accelerate the antibacterial behavior of Mg(OH)2 nanoplatelets. A novel possible antibacterial mechanism of Mg(OH)2 nanoparticles was consequently proposed. When contacting directly with a bacterial cell, Mg(OH)2 nanoparticles would enter into the cell through endocytosis and accumulate in vivo. Since there is over 70% water inside the cell, the Mg(OH)2 nanoparticles would inevitably dissolve and OH− would be released until an equilibrium is reached (pH of ~10). Therefore, the intracellular high pH would lead to cell death.