A series of MgO nanoparticles were prepared by first precipitating and isolating Mg(OH)2 nanoparticles from Mg(NO3)2 at three different temperatures using NaOH followed by their thermal decomposition also at three tem...A series of MgO nanoparticles were prepared by first precipitating and isolating Mg(OH)2 nanoparticles from Mg(NO3)2 at three different temperatures using NaOH followed by their thermal decomposition also at three temperature settings. The effects of temperature at which precipitation and thermal decomposition of the hydroxide occurred were studied to assess their influence on nanoparticle size and surface area. The synthesised nanoparticles were characterized using a suite of techniques including Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM) analysis. The average diameter range of MgO nanoparticles ranged between 15 and 35 nm, while for the precursor Mg(OH)2 it varied between 28 and 45 nm. The nanoparticle surface area obtained from BET studies was found in all cases to increase from 77 to 106.4 m2/g with increasing temperature of precipitation. Antibacterial activities of the prepared Mg(OH)2 and MgO nanoparticles were evaluated against the Gram-negative bacteria, Escherichia coli, and the Gram-positive bacteria, Staphylococcus aureus, using agar diffusion method. A correlation between surface area and antibacterial activity supported the mechanism of bacterial inactivation as the generation of reactive species. The Mg(OH)2 and MgO nanoparticles both exhibited pronounced bactericidal activity towards the Gram positive bacteria than Gram negative bacteria as indicated by the extend of the zone of inhibition around the nanoparticle.展开更多
文摘A series of MgO nanoparticles were prepared by first precipitating and isolating Mg(OH)2 nanoparticles from Mg(NO3)2 at three different temperatures using NaOH followed by their thermal decomposition also at three temperature settings. The effects of temperature at which precipitation and thermal decomposition of the hydroxide occurred were studied to assess their influence on nanoparticle size and surface area. The synthesised nanoparticles were characterized using a suite of techniques including Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Scanning Electron Microscope (SEM) analysis. The average diameter range of MgO nanoparticles ranged between 15 and 35 nm, while for the precursor Mg(OH)2 it varied between 28 and 45 nm. The nanoparticle surface area obtained from BET studies was found in all cases to increase from 77 to 106.4 m2/g with increasing temperature of precipitation. Antibacterial activities of the prepared Mg(OH)2 and MgO nanoparticles were evaluated against the Gram-negative bacteria, Escherichia coli, and the Gram-positive bacteria, Staphylococcus aureus, using agar diffusion method. A correlation between surface area and antibacterial activity supported the mechanism of bacterial inactivation as the generation of reactive species. The Mg(OH)2 and MgO nanoparticles both exhibited pronounced bactericidal activity towards the Gram positive bacteria than Gram negative bacteria as indicated by the extend of the zone of inhibition around the nanoparticle.
