In Vitro Viability Tests of New Ecofriendly Nanosystems Incorporating Essential Oils for Long-Lasting Conservation of Stone Artworks.

The study explores the application of natural biocides (oregano essential oil and eugenol, directly applied in solutions or encapsulated within silica nanocapsules) for safeguarding stone cultural heritage from biodeterioration, using green algae (Chlorococcum sp.) and cyanobacteria (Leptolyngbya sp.) as common pioneer biodeteriogens. Core-shell nanocontainers were built for a controlled release of microbicidal agents, a safe application of chemicals and a prolonged efficacy. The qualitative and quantitative evaluations of biocide efficiency at different doses were periodically performed in vitro, after six scheduled intervals of time (until 100 days). The release kinetics of composite biocide-embedding silica nanocapsules were characterized by the UV-Vis spectroscopy technique. Data showed both promising potential and some limitations. The comparative tests of different biocidal systems shed light on their variable efficacy against microorganisms, highlighting how encapsulation influences the release dynamics and the overall effectiveness. Both the essential oils showed a potential efficacy in protective antifouling coatings for stone artifacts. Ensuring compatibility with materials, understanding their differences in biocidal activity and their release rates becomes essential in tailoring gel, microemulsion or coating products for direct on-site application.

Science for art: multi-years' evaluations of biocidal efficacy in support of artwork conservation.

In recent decades, the relationship between Science and Art has been gradually strengthened through the use of diagnostic, conservation, and valorization technologies. New technologies can also be used to support the creation and durability of bio-artworks. Within such a context, starting from the Spring of 2014, we performed in situ experimentations to eventually increase the durability of the graphical artwork of William Kentridge on the Lungotevere embankments, whose creation was scheduled in the following years. We applied various combinations and concentrations of three different biocides (Algophase, Biotin R, and Preventol R80) and two water repellents (Hydrophase surfaces and Silo 111) on 34 test areas. However, the artist preferred to leave his artwork to a natural fading. Right before the realization of the graphical artwork "Triumph and Laments of Rome" in 2016, just the black biological colonizations mainly composed of cyanobacteria were removed through pressurized water. We monitored the artist's work through analyses of images and colorimetric variations and such drawings showed a duration of 4 years in the natural conditions of recolonization. Here we show how the recolonization of treated and control areas, analyzed with the same methods, showed an increased duration, 3 years longer than under natural conditions in the case of Preventol R80® and Biotin R® plus Silo 111®. The tested solutions showed differential effectiveness and multiple possibilities of use to support the maintenance of the artwork if the artist wanted to preserve his artwork for a longer period.