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Filamentous fungi are microorganisms that cause deterioration of structural materials due to their ecological plasticity and vegetative functions. Functionalised sol-gel based products can be used to control this kind of biodeterioration through the association to antifungal active additives which are trapped in the siloxane crosslinking. Bioactive additives and materials to control microbial growth have been gaining more attention over the years. However, due to the concern about their toxicity, bio-based approach has been explored. The aim of the present research was to obtain antifungal additives with nanoparticles synthesised with aqueous extract of Senna occidentalis L and silver or copper salts to obtain a functionalised sol-gel based product to control the biodeterioration of bricks. Nanoparticles were characterised by UV-vis spectroscopy, transmission electron microscopy and x-ray diffraction. Silver nanoparticles (15 nm) showed higher stability over time and proved to be active against Aspergillus versicolor and Cladosporium cladosporioides which were isolated from brick wall. The strains were selected due to their high frequency in mycobiota of biodeteriorated structural building materials. The silver nanoparticles were successfully integrated in a silane-based matrix to be applied in bricks. The samples were characterised by surface tension determination, contact angle measurement, water absorption determination, scanning electron microscopy and energy dispersive x-ray spectroscopy. Bricks with the lower concentration (2%) of the functionalised silane (3mercaptopropyltrimethoxy) showed to be efficient to prevent fungal biofilm development with 100% of inhibition against both strains.

Antimicrobial surfaces are required to obtain more hygienic indoor environments. There are biogenic compounds like terpenoids, from plant essential oils, with potential antimicrobial activity. Besides, modified montmorillonites are promising nanoscale carriers for these compounds. The aim of this research was to prepare antimicrobial coatings with funtionalized montmorillonite hybrid. Three monoterpene compounds from plant essential oils such as citral, citronellol and linalool were assessed to obtain an eco-friendly and cheap antifungal hybrid filler for coatings. A natural surfactant such as soybean lecithin was used as an organic modifier of the clay mineral. The synthetized hybrids were studied with X-ray diffraction (XRD) analysis, thermogravimetric Analysis (TG), Fourier-Transform Infrared (FTIR) spectroscopy, Zeta potential (ZP) and scanning electron microscopy (SEM). The modified montmorillonite with soybean lecithin and citronellol by 40% wt. showed higher antifungal activity. This bioactive hybrid achieved to impart its functionality into a waterborne paint formulated with 5% wt. in bioassays against three frequent and handful moulds Chaetomium globosum (KU936228), Alternaria alternata (KU936229) and Aspergillus fumigatus (KU936230).

Nowadays urban populations spend 90% of their time in buildings where microbial growth lead to hazardous environments which produce health problems characterized by irritation of the respiratory tract, infections, allergies and asthma. Some research lines seek to obtain antimicrobial materials to prevent such health problems. Green synthesis of different nanoparticles was carried out to explore their antimicrobial potential. Solutions of silver, copper, cerium, lanthanum and zinc salts were used as source of metal ions for the synthesis process. Aqueous plant extract from Senna occidentalis, a small shrub, was used, for the first time, as reducing and stabilizing agent to obtain additives to bioactive coatings. The stable synthesis products were evaluated by UV-vis spectroscopy and their antimicrobial properties were assessed. Other characterizations by transmission electron microscopy and Fourier transformed infrared spectroscopy were also performed. Silver and copper nanoparticles were stable over time. However, only silver nanoparticles showed antibacterial and antifungal activity and were used for obtaining antimicrobial waterborne acrylic paints. The formulation with 25 mg/100 g resulted in efficient inhibition of the fungal and bacterial biofilm.

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Concern over indoor fungal growth has increased over the last decades. Research that relates human health issues to the deterioration of indoor air quality due to microbiological pollutants have been accumulated (Rath et al. 2011;Weber 2012;Täubel and Hyvärinen 2015). In addition, since the 1980s, it has been registered that there is an increase in the occurrence of natural disasters such as floods and extreme rainfall, on a global scale, which has enhanced the problems related to biodeterioration in indoor buildings (Bloom et al. 2009;Chow et al. 2019; EASAC 2018). It is worth mentioning that these kinds of events are directly related to fungal growth since water is a key factor in the development of these microorganisms (Johansson et al. 2013;Møller et al. 2017). Considering the strong impact of indoor fungi on public health, several guidelines have been proposed from different European and North American institutions. These institutions include the

La preocupación creciente por el control de la colonización y crecimiento de hongos y bacterias en los interiores edilicios ha impulsado distintas líneas investigativas que comprenden el desarrollo de nuevas pinturas y recubrimientos con propiedades antimicrobianas que eviten el asentamiento de los microorganismos. Estas formulaciones contienen uno o más aditivos antimicrobianos llamados biocidas. Entre los productos investigados se destacan las nanopartículas de ciertos materiales metálicos (plata, cobre, selenio y oro) que han mostrado algún grado de bioactividad. Las nanopartículas se caracterizan por contar con propiedades dependientes del tamaño y la forma, a su vez, éstas son afectadas por el método y las condiciones de síntesis. Existe un creciente interés en desarrollar procesos de obtención de nanopartículas que sean amigables con el ambiente, es decir que eviten el uso de productos químicos cuestionados desde el punto de vista de su toxicidad. Esta tendencia enmarcada en la denominada química verde tiene como objetivos principales reducir los desechos, minimizar el uso de productos no seguros y beneficiar el uso de solventes y reactivos amigables con el ambiente. La síntesis verde de nanopartículas basada en el uso de extractos vegetales acuosos resulta promisoria por ser accesible, efectiva, segura, de bajo costo, no contaminante y por ofrecer vastas posibilidades. El objetivo de esta investigación fue desarrollar nuevos aditivos antimicrobianos de base nanotecnológica obtenidos por síntesis verde, aplicables en forma eficiente en la formulación de pinturas antimicrobianas que prevengan el biodeterioro. Para lograr este objetivo se trabajó en primer lugar en la obtención, caracterización y selección de las nanopartículas con mayor actividad tanto antibacteriana como antifúngica. En una siguiente etapa, se formularon y prepararon pinturas con los aditivos antimicrobianos desarrollados reemplazando los biocidas tradicionales que se usan en las pinturas comerciales fuertemente cuestionados desde el punto de vista de la salud y el impacto ambiental.

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