Ricerc@Sapienza

The colonization of microorganisms and their subsequent interaction with stone
substrates under different environmental conditions encourage deterioration of materials by multiple
mechanisms resulting in changes in the original color, appearance and durability. One of the emerging
alternatives to remedy biodeterioration is nanotechnology, thanks to nanoparticle properties such
as small size, no-toxicity, high photo-reactivity, and low impact on the environment. This study
highlighted the effects of ZnO-based nanomaterials of two bacteria genera isolated from the Temple of
Concordia (Agrigento’s Valley of the Temples in Sicily, Italy) that are involved in biodeterioration
processes. The antimicrobial activities of ZnO-nanorods (Zn-NRs) and graphene nanoplatelets
decorated with Zn-NRs (ZNGs) were evaluated against the Gram positive Arthrobacter aurescens and
two isolates of the Gram negative Achromobacter spanius. ZNGs demonstrated high antibacterial
and antibiofilm activities on several substrates such as stones with different porosity. In the case of
ZNGs, a marked time- and dose-dependent bactericidal effect was highlighted against all bacterial
species. Therefore, these nanomaterials represent a promising tool for developing biocompatible
materials that can be exploited for the conservation of cultural heritage. These nanostructures can be
successfully applied without releasing toxic compounds, thus spreading their usability.