Antibacterial activity of silver nanoparticles grafted on stone surface
Microbial colonization has a relevant impact on the deterioration of stone materials with consequences ranging from esthetic to physical and chemical changes. Avoiding microbial growth on cultural stones therefore represents a crucial aspect for their long-term conservation. The antimicrobial properties of silver nanoparticles (AgNPs) have been extensively investigated in recent years, showing that they could be successfully applied as bactericidal coatings on surfaces of different materials. In this work, we investigated the ability of AgNPs grafted to Serena stone surfaces to inhibit bacterial viability. A silane derivative, which is commonly used for stone consolidation, and Bacillus subtilis were chosen as the grafting agent and the target bacterium, respectively. Results show that functionalized AgNPs bind to stone surface exhibiting a cluster disposition that is not affected by washing treatments. The antibacterial tests on stone samples revealed a 50 to 80 % reduction in cell viability, with the most effective AgNP concentration of 6.7 μg/cm2. To our knowledge, this is the first report on antimicrobial activity of AgNPs applied to a stone surface. The results suggest that AgNPs could be successfully used in the inhibition of microbial colonization of stone artworks.
KeywordsSilver nanoparticles Conservation of cultural heritage Stone biodeterioration Bacillus subtilis Antibacterial activity
CSGI and Ministry for Education and Research (MIUR, PRIN2009-2009P2WEAT) are gratefully acknowledged for financial support. M.B. thanks the EU for financial support under the Marie Curie Actions - European Reintegration Grants (FP7-PEOPLE-2009-RG, Project number: 249319, SUPRACRYST). The authors also thank dr. Nicole Bonelli, CSGI, for the assistance with colorimetric measurements.
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