Gold-nanoparticles grafting for potential architectural and Cultural Heritage applications

Nanomaterials have been designed to guarantee the long-term restoration and preservation of cultural heritage; in particular, scientists are involved in the cleaning, the deacidification and the consolidation of different kinds of artistic substrates. Cleaning the surface of artworks is an irreversible and delicate intervention that implicates the replacement of shallow layer materials. In some cases, as hard materials such as marble and stone, this can be achieved using laser or plasma techniques. However, these procedures can produce local heating and mechanical shocks, especially for painted surfaces. Chemical methodologies are the favorite options because they may result more ecological, practical and not invasive. Nanoparticles (NPs) are produced using different materials such as metals, metal oxides, carbon, polymers and lipids. The potential of NPs for conservation of buildings has been established for the consolidation of decayed materials, production of de-polluting surfaces, self- cleaning or biocide surface enhancement to reduce biodeterioration. Suspensions of opportune NPs, even dispersed in polymeric matrices, have been tested and employed for their efficacy against biofouling of building wrappers. The aim of this work is the green synthesis and preparation of colloidal systems tailored to the preservation and consolidation of wall paintings, cements and stones. In particular, the present study will show the grafting of gold-nanoparticles on three different substrates: 1) montmorillonite clay, which was previously functionalized with a thiolic group, useful for application in the restoration and conservation of building materials; 2) glass surface, for the restauration of glass artifacts; 3) fabrics, for ‘wearable materials’ properties implementation. Unfortunately, under particular conditions, deterioration of an artwork may induce the nanoparticles release into the environment; in order to inhibit this undesired phenomenon, the colloidal nanoparticles could be stably bonded to the treated artwork (based on clay, glass or textiles), by means of a grafting sol-gel polymeric 3D-matrix.