Broad spectrum antimicrobial activity of Ca(Zn(OH)3)2·2H2O and ZnO nanoparticles synthesized by the sol–gel method

AbstractThe process of biodeterioration is one of the main problems affecting historical monuments and buildings. On rock surfaces, different types of microorganisms establish in the most adequate niches and accelerate degradation, leading to the irreversible loss of cultural heritage. Therefore, new ways to preserve cultural heritage must be urgently studied to prevent such damage. In this study, the broad-spectrum antimicrobial activity of calcium zinc hydroxide dehydrate [Ca(Zn(OH)3)2·2H2O] (CZ) and zinc oxide (ZnO) nanoparticles synthesized by the sol–gel method is examined against fungal and bacterial model organisms. The selected microbes were inhibited by both nanoparticles, yet CZ was the most effective, with a bactericidal activity of 1.25 to 5 mg/mL and a fungicidal activity of 0.625 mg/mL. Both nanoparticles caused structural damage to the evaluated fungal cells, resulting in morphological changes and affecting the germination of conidia. For the first time in the literature, the antibacterial activity and the mode of action of CZ are reported. In conclusion, CZ nanoparticles are shown to be potential candidates for the treatment of rock surfaces of built cultural heritage. HighlightsA dose–response effect was observed in the inhibition of microbial growth by nanoparticles.Calcium zinc hydroxide dehydrate showed greater diffusion in the agar with respect to zinc oxide.Calcium zinc hydroxide dehydrate exhibited bactericidal and fungicidal activity in the tested models.The evaluated nanoparticles caused irreversible damage to the conidia of fungi.