Abstract
Engineered nanomaterials (ENMs) can alter surface properties of cells and disturb cellular functions and gene expression through direct and indirect contact, exerting unintended impacts on human and ecological health. However, the effects of interactions among environmental factors, such as light, surrounding media, and ENM mixtures, on the mechanisms of ENM toxicity, especially at sublethal concentrations, are much less explored and understood. Therefore, we evaluated cell viability and outer membrane permeability of E. coli as a function of exposure to environmentally relevant concentrations of ENMs, including metal (n-Ag) and metal oxide (n-TiO2, n-Al2O3, n-ZnO, n-CuO, and n-SiO2) nanoparticles under dark and simulated sunlight illumination in MOPS, a synthetic buffer, and Lake Michigan Water (LMW), a freshwater medium. We found that light activates the phototoxicity of n-TiO2 and n-Ag by inducing significant increases in bacterial outer membrane permeability at sublethal doses (< 1 mg/L). Other ENMs, including n-ZnO, n-CuO, n-Al2O3, and n-SiO2, have small to minimal impacts. Toxicities of ENMs were greater in LMW than MOPS due to their different ionic strength and chemical composition. Physical and chemical interactions between n-TiO2 and n-Ag lead to amplified toxic effects of the ENM mixtures that are greater than the additive effects of individual ENMs acting alone. Our results revealed the significant sublethal bacterial stress exerted by ENMs and ENM mixtures at the cell surface in natural environments at low doses, which can potentially lead to further cellular damage and eventually impact overall ecological health.
Original language | English (US) |
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Article number | 174861 |
Journal | Science of the Total Environment |
Volume | 948 |
DOIs | |
State | Published - Oct 20 2024 |
Externally published | Yes |
Funding
Metal analysis of LMW was performed at the Northwestern University Quantitative Bio-element Imaging Center. XRD made use of the IMSERC Crystallography facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), and Northwestern University. The Nano Zetasizer was from the Keck-II facility of Northwestern University's NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-1720139). We are thankful to Dr. Han Fu, Dr. Yingqian Xiong, and Professor Jean-Fran\u00E7ois Gaillard for their help with analytical techniques and the instrument operation and maintenance associated with the research. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Metal analysis of LMW was performed at the Northwestern University Quantitative Bio-element Imaging Center. XRD made use of the IMSERC Crystallography facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), and Northwestern University. The Nano Zetasizer was from the Keck-II facility of Northwestern University's NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-1720139).
Keywords
- ENM mixtures
- Environmental conditions
- Metal-based nanoparticles
- Outer membrane injury
- Sublethal ENM concentrations
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal
- Pollution