Dissolution Behaviour of Metal-Oxide Nanomaterials in Various Biological Media
- DOI
- Language of the publication
- English
- Date
- 2022-12-21
- Type
- Article
- Author(s)
- Avramescu, Mary-Luyza
- Chénier, Marc
- Beauchemin, Suzanne
- Rasmussen, Pat
- Publisher
- MDPI
Abstract
Toxicological effects of metal-oxide-engineered nanomaterials (ENMs) are closely related to their distinct physical–chemical properties, especially solubility and surface reactivity. The present study used five metal-oxide ENMs (ZnO, MnO2, CeO2, Al2O3, and Fe2O3) to investigate how various biologically relevant media influenced dissolution behaviour. In both water and cell culture medium (DMEM), the metal-oxide ENMs were more soluble than their bulk analogues, with the exception that bulk-MnO2 was slightly more soluble in water than nano-MnO2 and Fe2O3 displayed negligible solubility across all tested media (regardless of particle size). Lowering the initial concentration (10 mg/L vs. 100 mg/L) significantly increased the relative solubility (% of total concentration) of nano-ZnO and nano-MnO2 in both water and DMEM. Nano-Al2O3 and nano-CeO2 were impacted differently by the two media (significantly higher % solubility at 10 mg/L in DMEM vs. water). Further evaluation of simulated interstitial lung fluid (Gamble’s solution) and phagolysosomal simulant fluid (PSF) showed that the selection of aqueous media significantly affected agglomeration and dissolution behaviour. The solubility of all investigated ENMs was significantly higher in DMEM (pH = 7.4) compared to Gamble’s (pH 7.4), attributable to the presence of amino acids and proteins in DMEM. All ENMs showed low solubility in Gamble’s (pH = 7.4) compared with PSF (pH = 4.5), attributable to the difference in pH. These observations are relevant to nanotoxicology as increased nanomaterial solubility also affects toxicity. The results demonstrated that, for the purpose of grouping and read-across efforts, the dissolution behaviour of metal-oxide ENMs should be evaluated using aqueous media representative of the exposure pathway being considered.
Plain language summary
Health Canada is responsible for regulating consumer and industrial products containing engineered nanomaterials (ENMs). Research funded by the Chemicals Management Plan is contributing to international efforts to evaluate the potential health risks posed by ENMs. The objective of this study is to investigate dissolution behaviour of three metal oxide ENMs: copper (II) oxide (CuO), nickel (II) oxide (NiO), titanium dioxide (TiO2). These metal oxides were selected based on their importance in consumer products and industrial applications in Canada. The dissolution tests were conducted in water and cell culture medium relevant for toxicology assays. The results showed that the solubility of the metal oxides decreased in the order CuO > NiO > TiO2, and that the solubility of each of the investigated ENMs was significantly higher than that of its traditional macro-scale counterpart, in both aqueous media. However, the metal oxide ENMs responded differently to the two aqueous media when comparing their solubility using low (10 mg/L) versus high (100 mg/L) initial concentration. In cell culture medium, nano-CuO and nano-NiO were more soluble at the higher initial concentration, whereas nano-TiO2 was less soluble at the higher initial concentration. In water, the opposite trend was observed. These results show the importance of evaluating the solubility of ENMs in biologically-relevant fluids at concentrations that correspond to toxicity assays, for the purpose of hazard assessment. This research has provided new information on the physical and chemical characteristics of ENMs currently in commerce in Canada, and has developed techniques that will contribute to the development of standardized solubility testing and screening approaches.
Subject
- Health,
- Health and safety