Inhibition of bacterial growth on marble stone of 18th century by treatment of nanoencapsulated essential oils

Controlling of cultural heritage biodeterioration is a serious problem in the world. Chemical biocides, used to killunwanted microorganism, can represent a risk for human health and environment, and interfere with the restorationmaterial. Natural biocides could represent a valid alternative to conventional ones. In this study wereport the use of nanocapsules suspensions (NCs) loaded with Origanum vulgare and Thymus capitatus essentialoils (EOs) to contrast the development of bacterial growth of two microrganisms (Escherichia coli and Kokuriarhizophila) on the marble stone from 18th century church altar. No structural change was observed on the stoneafter treatment with the aqueous suspension containing nanoparticles as evidenced by SEM-EDX analysis. Thenanostructurate systems (EO-NCs) were able to inhibit the bacterial grow on the stone pretreated with bacterialinoculum as showed by agar discs contact test. Nanocapsules, based on biodegradable and biocompatiblepolymer (poly(?-caprolactone)), loaded with thyme EO are more efficient than nanocapsules loaded with oreganoEO. The obtained results evidenced the potential of these natural biocides in the treatment of biodeterioratedcultural heritage.