Optimization and application of the misting method with silver nanoparticles for disinfection of the historical objects

The results presented here constitute the first report concerning the disinfection of such materials as cotton (model studies) and paper, parchment, canvas, wood (historical objects). The aim of this study was to establish conditions for silver nanoparticles (AgNPs) misting disinfection, evaluate changes in material strength and colour after disinfection and assess the effect of disinfection on historical objects. Effective bacterial disinfection conditions were determined for cotton: 8 mistings with 45 ppm AgNPs, two mistings with 90 ppm AgNPs, and for moulds - 6 mistings with 90 ppm AgNPs (10-100 nm). The differences between the sensitivity of microorganisms (Escherichia coli, Staphylococcus aureus, Aspergillus niger, Bacillus subtilis) to disinfection were confirmed. On the historical materials, the presence of moulds at a level of 9.5 x 10(4) to 4.5 x 10(11) cfu cm(-2) was recorded. The most effective mould reduction was observed on wood and paper map (R >= 99%), with lower values on parchment and canvas (R = 68-80%). It was also noted that cotton colour and strength parameters do not change after misting 8 times with 90 ppm AgNPs. It seems therefore that the AgNPs misting disinfection method may be an alternative to other methods, assuming the particularly durable retention of AgNPs on the material surface. (C) 2012 Elsevier Ltd. All rights reserved.