22 research outputs found
Redox-Active Nanomaterials For Nanomedicine Applications
Nanomedicine utilizes the remarkable properties of nanomaterials for the diagnosis, treatment, and prevention of disease. Many of these nanomaterials have been shown to have robust antioxidative properties, potentially functioning as strong scavengers of reactive oxygen species. Conversely, several nanomaterials have also been shown to promote the generation of reactive oxygen species, which may precipitate the onset of oxidative stress, a state that is thought to contribute to the development of a variety of adverse conditions. As such, the impacts of nanomaterials on biological entities are often associated with and influenced by their specific redox properties. In this review, we overview several classes of nanomaterials that have been or projected to be used across a wide range of biomedical applications, with discussion focusing on their unique redox properties. Nanomaterials examined include iron, cerium, and titanium metal oxide nanoparticles, gold, silver, and selenium nanoparticles, and various nanoscale carbon allotropes such as graphene, carbon nanotubes, fullerenes, and their derivatives/variations. Principal topics of discussion include the chemical mechanisms by which the nanomaterials directly interact with biological entities and the biological cascades that are thus indirectly impacted. Selected case studies highlighting the redox properties of nanomaterials and how they affect biological responses are used to exemplify the biologically-relevant redox mechanisms for each of the described nanomaterials
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles
Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles
Quantification of Carbon Nanotubes in Environmental Matrices: Current Capabilities, Case Studies, and Future Prospects
Carbon
nanotubes (CNTs) have numerous exciting potential applications
and some that have reached commercialization. As such, quantitative
measurements of CNTs in key environmental matrices (water, soil, sediment,
and biological tissues) are needed to address concerns about their
potential environmental and human health risks and to inform application
development. However, standard methods for CNT quantification are
not yet available. We systematically and critically review each component
of the current methods for CNT quantification including CNT extraction
approaches, potential biases, limits of detection, and potential for
standardization. This review reveals that many of the techniques with
the lowest detection limits require uncommon equipment or expertise,
and thus, they are not frequently accessible. Additionally, changes
to the CNTs (e.g., agglomeration) after environmental release and
matrix effects can cause biases for many of the techniques, and biasing
factors vary among the techniques. Five case studies are provided
to illustrate how to use this information to inform responses to real-world
scenarios such as monitoring potential CNT discharge into a river
or ecotoxicity testing by a testing laboratory. Overall, substantial
progress has been made in improving CNT quantification during the
past ten years, but additional work is needed for standardization,
development of extraction techniques from complex matrices, and multimethod
comparisons of standard samples to reveal the comparability of techniques
Agglomeration of <i>Escherichia coli</i> with Positively Charged Nanoparticles Can Lead to Artifacts in a Standard <i>Caenorhabditis elegans</i> Toxicity Assay
The
increased use and incorporation of engineered nanoparticles
(ENPs) in consumer products requires a robust assessment of their
potential environmental implications. However, a lack of standardized
methods for nanotoxicity testing has yielded results that are sometimes
contradictory. Standard ecotoxicity assays may work appropriately
for some ENPs with minimal modification but produce artifactual results
for others. Therefore, understanding the robustness of assays for
a range of ENPs is critical. In this study, we evaluated the performance
of a standard <i>Caenorhabditis elegans</i> (<i>C. elegans</i>) toxicity assay containing an <i>Escherichia coli</i> (<i>E. coli</i>) food supply with silicon, polystyrene, and
gold ENPs with different charged coatings and sizes. Of all the ENPs
tested, only those with a positively charged coating caused growth
inhibition. However, the positively charged ENPs were observed to
heteroagglomerate with <i>E. coli</i> cells, suggesting
that the ENPs impacted the ability of nematodes to feed, leading to
a false positive toxic effect on <i>C. elegans</i> growth
and reproduction. When the ENPs were tested in two alternate <i>C. elegans</i> assays that did not contain <i>E. coli</i>, we found greatly reduced toxicity of ENPs. This study illustrates
a key unexpected artifact that may occur during nanotoxicity assays
Agglomeration of <i>Escherichia coli</i> with Positively Charged Nanoparticles Can Lead to Artifacts in a Standard <i>Caenorhabditis elegans</i> Toxicity Assay
The
increased use and incorporation of engineered nanoparticles
(ENPs) in consumer products requires a robust assessment of their
potential environmental implications. However, a lack of standardized
methods for nanotoxicity testing has yielded results that are sometimes
contradictory. Standard ecotoxicity assays may work appropriately
for some ENPs with minimal modification but produce artifactual results
for others. Therefore, understanding the robustness of assays for
a range of ENPs is critical. In this study, we evaluated the performance
of a standard <i>Caenorhabditis elegans</i> (<i>C. elegans</i>) toxicity assay containing an <i>Escherichia coli</i> (<i>E. coli</i>) food supply with silicon, polystyrene, and
gold ENPs with different charged coatings and sizes. Of all the ENPs
tested, only those with a positively charged coating caused growth
inhibition. However, the positively charged ENPs were observed to
heteroagglomerate with <i>E. coli</i> cells, suggesting
that the ENPs impacted the ability of nematodes to feed, leading to
a false positive toxic effect on <i>C. elegans</i> growth
and reproduction. When the ENPs were tested in two alternate <i>C. elegans</i> assays that did not contain <i>E. coli</i>, we found greatly reduced toxicity of ENPs. This study illustrates
a key unexpected artifact that may occur during nanotoxicity assays