Toxicity of TiO2, ZnO, and SiO2 Nanoparticles in Human Lung Cells: Safe-by-Design Development of Construction Materials

Abstract

Rapid progress in the development of highly efficient nanoparticle-based construction technologies has not always been accompanied by a corresponding understanding of their effects on human health and ecosystems. In this study, we compare the toxicological effects of pristine TiO2, ZnO, SiO2, and coated SiO2 nanoparticles, and evaluate their suitability as additives to consolidants of weathered construction materials. First, water soluble tetrazolium 1 (WST-1) and lactate dehydrogenase (LDH) assays were used to determine the viability of human alveolar A549 cells at various nanoparticle concentrations (0–250 μg mL−1). While the pristine TiO2 and coated SiO2 nanoparticles did not exhibit any cytotoxic effects up to the highest tested concentration, the pristine SiO2 and ZnO nanoparticles significantly reduced cell viability. Second, as all developed nanoparticle-modified consolidants increased the mechanical strength of weathered sandstone, the decisive criterion for the selection of the most suitable nanoparticle additive was as low toxicity as possible. We believe that this approach would be of high importance in the industry, to identify materials representing top functional properties and low toxicity, at an early stage of the product development.

Potential of Advanced Consolidants for the Application on Sandstone

“…Concerning the preparation of consolidants, five commercially available metal oxide nanoparticles were used, including Aeroxide ® TiO 2 P25 (Evonik Industries, Essen, Germany), Aerosil ® SiO 2 200 Pharma, Aerosil ® SiO 2 R805, Aerosil ® SiO 2 R9200 (all Evonik Industries, Essen, Germany) and NanoZnO (Bochemie, Bohumin, Czech Republic). Detailed characteristics of the nanoparticles are provided in reference [11]. Dynasylan 40 was obtained from Evonik Industries (Essen, Germany), isopropanol (IPA), dibutyltin dilaurate (DBTL), n-octylamine, were all from Sigma-Aldrich (St. Louis, MO, USA), and Ca(OH) 2 (Penta, Prague, Czech Republic).…”

“…Another strategy involves the incorporation of elastic segments, such as hydroxyl-terminated polydimethylsiloxane (PDMS), into the xerogel structure; these segments effectively removed the stress caused by capillary pressure [5][6][7][8][9]. Another more general approach is based on the incorporation of various oxide nanoparticles, such as SiO 2 , TiO 2 , Al 2 O 3 and ZnO (so-called particle-modified consolidants, PMC) [3,8,[10][11][12][13][14][15]. Due to the increase in the pore size of PMC-based xerogel and the improvement of its mechanical properties, cracking was reduced, and the consolidation effect enhanced.…”

“…The Czech Republic is particularly suitable in this respect because it is rich in sandstone quarries, meaning that a wide range of samples differing in texture and mechanical properties are available. Our previous studies have shown that sandstone from the Msene quarry in Central Bohemia is suitable for the evaluation of consolidation performance because it is characterized by high-porosity and relatively low mechanical strength [11,13,14]. This sandstone is characterized by high-purity (over 95% of quartz and a small amount of binder), homogeneity and a well-defined monomodal porous system with a narrow pore-size distribution.…”

“…Therefore, in this study, we focus on the aspect of durability and use it as a criterion for the assessment of the consolidation outcome. Specifically, we consolidate Czech-quarried sandstone by various consolidant formulations, including two TEOS-based commercial products (Remmers KSE OH, SurfaPore FX SB), a self-developed TEOS-based PMC consolidant [11], and two self-developed phosphate-based consolidants. Afterwards, we artificially weather the treated samples and determinethe durability of each type of sandstone consolidation by performing mechanical tests on a micro-(nanoindentation) and macroscale (drilling resistance measurements).…”

Green Synthesis and Characterization of Zinc Oxide Nanoparticles Using Eucalyptus globules and Their Fungicidal Ability Against Pathogenic Fungi of Apple Orchards

“…Moreover, the anti-bacterial potential of Zinc oxide nanoparticles was observed to be effective than that of Zinc oxide, essentially classified due to the smaller particles comprising a superior surface-dependent to amount of volume, which exhibits significant anti-bacterial properties [15]. ZnNPs also had substantial toxicity against cancer cells as discovered by various researchers [16,17]. ZnNPs are also considered to be top photocatalysts, which are employed in sanitizing wastewater, and decay or reduce herbicides and pesticides [1].…”