Utilization of TiO₂ Nanoparticles to Protect Limestone Artifacts against Microorganisms Attack

Limestone artifacts are susceptible to attack by bacteria and fungi. This study aims to explore the utilization of titanium dioxide (TiO₂) nanoparticles for protecting limestone artifacts against fungal attack. Isolate microorganisms, primarily fungi, were identified by scanning electron microscope (SEM) and light microscope (LM). Six different fungal species were detected, Fusarium solani, Stemphylium sp., Aspergillus niger, A. flavus, A. versicolor and Curvularia geniculata along with Actinomyces spp. All of these microorganisms caused deterioration of the elemental contents of the used stone. Both Actinomyces spp. and the fungi were able to consume calcium carbonate as a carbon source, reducing the content of all the detected elements, including (e.g. silica, alumina and magnesia etc.) compared to the control sample. Coating of the surface of limestone slabs with a consolidated mixture formed of 2% TiO₂ nanoparticles dissolved in B-72 at a concentration of 5% and its effects on A. niger colonization were assessed. Coating of the slab surfaces with TiO₂ nanoparticles resulted in good consolidation, with these nanoparticles displaying excellent antifungal activity; suggesting that coating of limestone artifacts with TiO₂ nanoparticles can protect them against fungal activity.