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In the last decade, worldwide research has focused on innovative natural biocides and the development of organic and inorganic nanomaterials for long-lasting reliability. In this work, the biocide effects of two different biocides encapsulated in two different silica nanosystems for a multifunctional coating have been performed through in vitro tests, by using Chlorococcum sp. as a common stone biodeteriogen. Zosteric sodium salt (ZS), a green biocide, was compared with the commercial biocide, 2-mercaptobenzothiazole (MBT), widely used in the treatment of cultural heritage. The analyzed systems are the following: silica nanocapsules (NC) and silica nanoparticles (MNP) not loaded with biocides, two nanosystems loaded with ZS and MBT, and free biocides. The qualitative and quantitative evaluations of biocide efficiency were performed periodically, analyzing pigment autofluorescence to discriminate between active and inactive/dead cells. The analyses showed multiple differences. All the nanocontainers presented an initial reduction in chlorophyll's autofluorescence. For the free biocide, the results highlighted higher efficiency for MBT than ZS. Finally, the nanosystems loaded with the different biocides highlighted a higher activity for nanocontainers loaded with the commercial biocide than the green product, and better efficiency for MNP in comparison with NC. [ABSTRACT FROM AUTHOR]

In the last decade, worldwide research has focused on innovative natural biocides and the development of organic and inorganic nanomaterials for long-lasting reliability. In this work, the biocide effects of two different biocides encapsulated in two different silica nanosystems for a multifunctional coating have been performed through in vitro tests, by using Chlorococcum sp. as a common stone biodeteriogen. Zosteric sodium salt (ZS), a green biocide, was compared with the commercial biocide, 2-mercaptobenzothiazole (MBT), widely used in the treatment of cultural heritage. The analyzed systems are the following: silica nanocapsules (NC) and silica nanoparticles (MNP) not loaded with biocides, two nanosystems loaded with ZS and MBT, and free biocides. The qualitative and quantitative evaluations of biocide efficiency were performed periodically, analyzing pigment autofluorescence to discriminate between active and inactive/dead cells. The analyses showed multiple differences. All the nanocontainers presented an initial reduction in chlorophyll’s autofluorescence. For the free biocide, the results highlighted higher efficiency for MBT than ZS. Finally, the nanosystems loaded with the different biocides highlighted a higher activity for nanocontainers loaded with the commercial biocide than the green product, and better efficiency for MNP in comparison with NC.

In the last decade many commercial biocides were gradually banned for toxicity. This work reports, for the first time, the synthesis and characterization of silica nanocontainers loaded with a natural product antifoulant (NPA), the zosteric sodium salt which is a non-commercial and environmentally friendly product with natural origin. The synthesis approach is a single step dynamic self-assembly with tetraethoxysilane (TEOS) as silica precursor. Unlike conventional mesoporous silica nanoparticles, the structure of these silica nanocontainers provides loading capacity and allows prolonged release of biocide species. The obtained nanocapsules have been characterized morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The encapsulation was checked by FTIR ATR spectroscopy and thermogravimetric analyses. The results of the release studies show the great potential of the here presented newly developed nanofillers in all applications where a controlled release of non-toxic and environmentally friendly biocides is required. [ABSTRACT FROM AUTHOR]

The conservation of stone monuments is a constant concern due to their continuous weathering, in which biofouling plays a relevant role. To enhance the effectiveness of biocidal treatments and to avoid environmental issues related to their possible toxicity, this research aims at formulating and characterizing a coating charged with an eco-friendly biocide and showing hydrophobic properties. For this purpose, zosteric sodium salt—a natural biocide product—has been encapsulated into two silica nanocontainers and dispersed into a tetraethoxysilane-based (TEOS) coating also containing TiO2 nanoparticles. The coatings were applied on four different types of stone: brick, mortar, travertine, and Carrara marble. The effectiveness of the coating formulations and their compatibility concerning the properties of coated stones were assessed. The results showed that all coatings conferred a hydrophobic character to the substrate, as demonstrated by the increase of the static contact angle and the reduction in the capillary water absorption coefficient. The transmission of water vapor of the natural stones was preserved as well as their natural aspect. Furthermore, the coatings were homogeneously distributed on the surface and crack-free. Therefore, the protective capability of the coatings was successfully demonstrated. [ABSTRACT FROM AUTHOR]