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). Funded by Health Canada’s Chemicals Management Plan, the present study investigated how various biologically-relevant media influenced dissolution behaviour of five metal-oxide ENMs: zinc (II) oxide (ZnO), manganese (IV) oxide (MnO2), cerium (IV) oxide (CeO2), aluminum oxide (Al2O3), and iron (III) oxide (Fe2O3). These metal oxides were selected based on their importance in consumer products and industrial applications in Canada. The dissolution tests were conducted in water, cell culture medium relevant for toxicology assays (DMEM), and two simulated lung fluids (simulated interstitial lung fluid and phagolysosomal simulant fluid). The results showed that in both water and cell culture medium, 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. Fe2O3 displayed negligible solubility across all tested media (regardless of particle size). Lowering the initial concentration significantly increased solubility of nano-ZnO and nano-MnO2 in both water and DMEM. All tested ENMs showed low solubility in simulated interstitial lung fluid (pH 7.4) compared with phagolysosomal simulant fluid (pH 4.5), attributable to the difference in pH. Their lower solubility in simulated interstitial lung fluid compared with cell culture medium (pH 7.4) was attributed to the presence of aminoacids and proteins in DMEM. These results are relevant to nanotoxicology as increased nanomaterial solubility also affects toxicity. This research demonstrates that, for the purpose of grouping and read-across efforts, dissolution behaviour of metal oxide ENMs should be evaluated using aqueous media representative of the exposure pathway being considered. The results contribute to international efforts to evaluate the potential health risks posed by ENMs.
Subject
- Health,
- Health and safety