Antifungal applications for nano-additives synthesized with a bio-based approach

Abstract

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.

Mycological studies as a tool to improve the control of building materials biodeterioration

“…Then, it is necessary to protect the monuments from where the species were isolated. This protection can be performed through the application of antifungal coatings on the materials in order to control the fungal deterioration [43].…”

Perspectives for antimicrobial nanomaterials in cultural heritage conservation

“…Although a variety of other synthetic approaches have also been used, including the use of microorganisms, so-called biosynthesis (8%), used for ZnO, 49 Cu NPs, 50 and Ag NPs. 16,51 Electrochemical methods (4%) have also been used to prepare ZnO 19 and Cu NPs, 52 and sonochemical methods (4%) are currently trending as a convenient, rapid, and cost-effective route to obtain NPs such as ZnO. 53,54 Physical vapor deposition has also been used for the synthesis of In-doped ZnO.…”

Copper Surfaces in Biofilm Control

“…Furthermore, the use of copper materials on membrane systems (i.e., reverse osmosis membranes) or in dental care procedures has also been explored by the scientific community, however, at a lower extent (5% and 7% of the manuscripts works). The remaining 7% of original studies were related with the petrochemical industry (1.7%) [ 45 ], construction sector–bricks (1.7%) [ 46 ], food contacting surfaces (1.7%) [ 47 ] and space flight materials (1.7%) [ 48 ].…”

“…Copper is a widely used material due to its interesting workability characteristics and corrosion resistance. In addition to the applications described above, the antibacterial and antibiofilm properties of copper are relevant for many other applications such as in the food industry [ 121 ], fuel and oil facilities [ 45 ], construction sector [ 46 ] or even in space flight or space station equipment [ 48 ]. Dygico, et al [ 122 ] tested different materials that can be found in the mushroom production environment such as SS, aluminum, rubber, polypropylene, polycarbonate, concrete, borosilicate glass and copper and found that the use of copper reduced significantly the number of culturable Listeria monocytogens adhered on the surface [ 122 ].…”

“…Biofilm development in buildings is a significant concern as bacteria, fungi and algae in building biofilms are responsible for biodeterioration and may be related to some health issues such as allergies caused by fungal pathogens [ 123 ]. Gámez-Espinosa, et al [ 46 ] developed antifungal additives with copper- and silver-NPs synthesized with an aqueous extract of Senra occidentalis L. A functionalized sol–gel-based product was produced to apply on bricks in order to avoid biodeterioration.…”