Protection of 18th century paper using antimicrobial nano-magnesium oxide.

Magnesium oxide nanoparticles (MgO NPs) have attracted considerable interest as antimicrobial agents in a wide variety of applications. We report a simple synthetic route towards MgO NPs (average diameter 10 nm) possessing potent antibacterial activity against both Gram-negative and Gram-positive bacteria. Detailed electron microscopy studies show how these particles induce oxidative stress, cell membrane leakage and cell death in bacteria at low NP concentrations, but remain non-toxic to eukaryotic cells. Applying a homogeneous dispersion of these nanoparticles on 18th century paper proved to be a highly effective means of preventing bacterial colonisation without altering the appearance of the paper samples, thus opening the doors to the use of these colourless, low-cost, and scalable nanoparticles for preventing biodeterioration in a range of paper-based objects and surfaces. • Nano-magnesium oxide particles (MgO NPs) of average size of around 10 nm have been synthesised using a simple one-pot synthesis. • The MgO NPs offer potent bactericidal activity but are non-toxic to mammalian cells at the same concentrations. • A combination of electron microscopy techniques shows how these nanoparticles produce oxidative stress, followed by cell membrane leakage and death. • The MgO NPs prevented bacterial colonisation of 18th century papers from the Archives of the Spanish Royal Botanic Garden. [ABSTRACT FROM AUTHOR]