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ROS activity in carbonaceous nanoparticles : the influence of surface area and chemistry

Malmborg, Vilhelm LU orcid ; Elam, Derek Alexander ; Rissler, Jenny LU ; Clausen, Per Axel ; di battista, veronica ; Vogel, Ulla ; Wohlleben, Wendel and Jacobsen, Nicklas Raun (2024) NANOTOX 2024
Abstract
Carbon Black (CB), graphene, and nanodiamond are distinct carbonaceous insoluble nanoparticles. Reactive Oxygen Species (ROS) associated with these particles play a significant role in both in vivo and in vitro toxicity evaluations. Accurate assessment of ROS activity is relevant for toxicity screening and in ensuring safe working environments as well as guiding the innovation by safe-and-sustainable-by-design principles. Our study investigates the ROS activity of 13 CB, 6 graphene, and 3 nanodiamond samples, employing various techniques and assays, alongside the exploration of surface-specific physicochemical properties to understand observed differences in ROS activity among nanomaterials (figure 1). We utilized Electron Spin Resonance... (More)
Carbon Black (CB), graphene, and nanodiamond are distinct carbonaceous insoluble nanoparticles. Reactive Oxygen Species (ROS) associated with these particles play a significant role in both in vivo and in vitro toxicity evaluations. Accurate assessment of ROS activity is relevant for toxicity screening and in ensuring safe working environments as well as guiding the innovation by safe-and-sustainable-by-design principles. Our study investigates the ROS activity of 13 CB, 6 graphene, and 3 nanodiamond samples, employing various techniques and assays, alongside the exploration of surface-specific physicochemical properties to understand observed differences in ROS activity among nanomaterials (figure 1). We utilized Electron Spin Resonance spectroscopy (EPR) at temperatures of 196 °C and 20 °C to evaluate bulk total spin-count. Nanoparticle-induced ROS activity at 20 °C was measured using acellular and cellular DCFH2-DA assays, as well as EPR with the CPH spin-probe (EPR-CPH). Additionally, we measured the hemolytic activity of selected test compounds, as ROS generation has also been associated with increased hemolytic potential, the capacity to disrupt red blood cells membrane. Hemolytic activity depends on a variety of phys-chem factors and may be useful as a preliminary cytotoxicity indicator. Specific surface area (SSA) determined by BET analysis and surface composition studied via x-ray photoelectron spectroscopy (XPS) were investigated to find correlations with the observed ROS activity. The elemental composition analysis focused on carbon, oxygen, sulfur, and nitrogen, and carbon sp2/sp3 hybridization. We found a high correlation in ROS activity per unit mass across different assessment methods, notably with SSA emerging as the primary predictor [r=0.86-0.92]. When normalized by SSA, the ROS surface activity covered a 4-fold range only (CB and graphene). This should be compared to a 100-fold range for the ROS activity assessed per unit mass. Interestingly, the bulk EPR measurements showed no clear trends or correlations with ROS activity or SSA, indicating a minimal contribution of bulk free electrons to particle ROS activity. The XPS analysis confirmed predominantly carbonaceous surfaces with minor traces of oxygen, sulfur, and nitrogen. Multiple linear regression analysis incorporating the surface composition suggested that ROS surface activity increased with carbon sp2-hybridization, while oxygen and sulfur surface functional groups pacified the ROS surface activity. This understanding can contribute to explaining nanomaterial toxicity mechanisms and have broader implications for carbonaceous air pollutants. However, the interpretation of our model may need refinement considering potential contributions from surface functional groups with additional, specific reaction pathways. (Less)
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organization
publishing date
type
Contribution to conference
publication status
published
subject
conference name
NANOTOX 2024
conference location
Venice, Italy
conference dates
2024-09-23 - 2024-09-25
language
English
LU publication?
yes
id
92a17ba1-b0ed-4a16-877e-614ba85cc425
date added to LUP
2026-02-06 12:11:38
date last changed
2026-02-26 10:43:04
@misc{92a17ba1-b0ed-4a16-877e-614ba85cc425,
  abstract     = {{Carbon Black (CB), graphene, and nanodiamond are distinct carbonaceous insoluble nanoparticles. Reactive Oxygen Species (ROS) associated with these particles play a significant role in both in vivo and in vitro toxicity evaluations. Accurate assessment of ROS activity is relevant for toxicity screening and in ensuring safe working environments as well as guiding the innovation by safe-and-sustainable-by-design principles. Our study investigates the ROS activity of 13 CB, 6 graphene, and 3 nanodiamond samples, employing various techniques and assays, alongside the exploration of surface-specific physicochemical properties to understand observed differences in ROS activity among nanomaterials (figure 1). We utilized Electron Spin Resonance spectroscopy (EPR) at temperatures of  196 °C and 20 °C to evaluate bulk total spin-count. Nanoparticle-induced ROS activity at 20 °C was measured using acellular and cellular DCFH2-DA assays, as well as EPR with the CPH spin-probe (EPR-CPH). Additionally, we measured the hemolytic activity of selected test compounds, as ROS generation has also been associated with increased hemolytic potential, the capacity to disrupt red blood cells membrane. Hemolytic activity depends on a variety of phys-chem factors and may be useful as a preliminary cytotoxicity indicator. Specific surface area (SSA) determined by BET analysis and surface composition studied via x-ray photoelectron spectroscopy (XPS) were investigated to find correlations with the observed ROS activity. The elemental composition analysis focused on carbon, oxygen, sulfur, and nitrogen, and carbon sp2/sp3 hybridization. We found a high correlation in ROS activity per unit mass across different assessment methods, notably with SSA emerging as the primary predictor [r=0.86-0.92]. When normalized by SSA, the ROS surface activity covered a 4-fold range only (CB and graphene). This should be compared to a 100-fold range for the ROS activity assessed per unit mass. Interestingly, the bulk EPR measurements showed no clear trends or correlations with ROS activity or SSA, indicating a minimal contribution of bulk free electrons to particle ROS activity. The XPS analysis confirmed predominantly carbonaceous surfaces with minor traces of oxygen, sulfur, and nitrogen. Multiple linear regression analysis incorporating the surface composition suggested that ROS surface activity increased with carbon sp2-hybridization, while oxygen and sulfur surface functional groups pacified the ROS surface activity. This understanding can contribute to explaining nanomaterial toxicity mechanisms and have broader implications for carbonaceous air pollutants. However, the interpretation of our model may need refinement considering potential contributions from surface functional groups with additional, specific reaction pathways.}},
  author       = {{Malmborg, Vilhelm and Elam, Derek Alexander and Rissler, Jenny and Clausen, Per Axel and di battista, veronica and Vogel, Ulla and Wohlleben, Wendel and Jacobsen, Nicklas Raun}},
  language     = {{eng}},
  month        = {{09}},
  title        = {{ROS activity in carbonaceous nanoparticles : the influence of surface area and chemistry}},
  url          = {{https://lup.lub.lu.se/search/files/241605334/NANOTOX2024_FINAL_Optimized.pdf}},
  year         = {{2024}},
}