Molecular tailoring of nanostructured materials for a sustainable preventive conservation of Cultural Heritage

Summary In this study, two eco-friendly nanostructured systems were designed for a controlled release of protective agents, commonly used in traditional restoration treatments, for the preservation of metal and stone artifacts. ?-Cyclodextrin and its derivative were used as nanocarriers, since their capability to form "host-guest" complexes with hydrophobic molecules. The loaded agents were commercial products: 1H-Benzotriazole (BTA) and BIOTIN R®, commonly used, respectively, as corrosion inhibitor of copper-based artifacts and as biocide for stone protection against the proliferation of algae and lichens. Motivation Despite a general good preservative effect, commercial products can be often toxic and/or easily subjected to leaching, resulting in a not long lasting intervention. In order to obtain non-toxic systems and to increase the durability of the protective treatments, two different systems were developed by loading the chemical agents in suitable nanocarriers, which could be, then, applied as polymeric or crosslinked coating on the surface of the artifacts. Results An organic system based on ?-Cyclodextrin/BTA complex was produced for the corrosion inhibition of Cu-based surfaces. An organic/inorganic hybrid system, based on ?-Cyclodextrin/BIOTIN R® supported on mesoporous silica, was developed for the protection of stone biodeterioration. Both systems were characterized by surface chemical analysis (XPS) and structural analysis by X-ray diffraction (XRD). The kinetics of release of ?-Cyclodextrin/BTA system was investigated by UV-VIS spectroscopy in 3%NaCl solution in order to simulate the marine environment. The kinetics of release of the ?-Cyclodextrin/BIOTIN R® system was investigated in acidic solution in order to simulate an urban polluted environment (rain water). The gradual release of the protective agent encourages the use of ?-Cyclodextrin/BTA system as non-toxic, self-healing and long-lasting corrosion inhibitor of Cu-based alloys. Acknowledgements. This work was financially supported by the PON03PE_00214_1 TECLA Project: "Nanotecnologie e nanomateriali per i Beni Culturali", Distretto di Alta Tecnologia per l'Innovazione nel settore dei Beni Culturali della Regione Sicilia.