Preparation and antibacterial activity of magnesium oxide nanoplates via sol-gel process

Magnesium oxide (MgO) nanopowders were synthesised by a sol-gel method with different amounts of ammonium hydroxide (NH₃·H₂O) and characterised by a combination of thermo gravimetric analysis, X-ray diffraction and transmission electron microscopy. It was found that the structure and morphology of MgO nanopowders can be regulated by the addition of NH₃·H₂O. When an appropriate amount of NH₃·H₂O was added into the reaction system, plate-like nanoMgO was obtained. The antibacterial activity of MgO nanoplates was also investigated by the minimum inhibition concentration (MIC) test and bactericidal efficacy against Escherichia coli (E. coli, ATCC 25922). The tested results revealed that the MgO nanoplates have great antibacterial effect with an MIC value of 600 mg/l and the bactericidal rate was about 99.8% at a concentration of 500 mg/l. Furthermore, the effect of NH₃·H₂O on the structure and morphology of MgO nanopowders and on the growth mechanism are briefly discussed. The hydroxide ion of NH₃·H₂O, in favour of Mg(OH)₂ generation in the precursors, is essential for the formation of MgO nanoplates.