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Smith JN, Skinner AW. Translating nanoparticle dosimetry from conventional in vitro systems to occupational inhalation exposures. JOURNAL OF AEROSOL SCIENCE 2021; 155:10.1016/j.jaerosci.2021.105771. [PMID: 35979194 PMCID: PMC9380399 DOI: 10.1016/j.jaerosci.2021.105771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
As encouraged by Toxicity Testing in the 21st Century, researchers increasingly apply high-throughput in vitro approaches to identify and characterize nanoparticle hazards, including conventional aqueous cell culture systems to assess respiratory hazards. Translating nanoparticle dose from conventional toxicity testing systems to relevant human exposures remains a major challenge for assessing occupational risk of nanoparticle exposures. Here, we explored existing computational tools and data available to translate nanoparticle dose metrics from cellular test systems to inhalation exposures of silver nanoparticles in humans. We used the Multiple-Path Particle Dosimetry (MPPD) Model to predict nanoparticle deposition of humans exposed to 20 and 110 nm silver nanoparticles at 0.9 μg/m3 over an 8 h period, the proposed National Institute of Occupational Safety and Health (NIOSH) recommended exposure limit (REL). MPPD predicts 8.1 and 3.7 μg of silver deposited in an 8 h period for 20 and 110 nm nanoparticles, respectively, with 20 nm particles displaying nearly 11-fold higher total surface area deposited. Peak deposited nanoparticle concentrations occurred more proximal in the pulmonary tract compared to mass deposition patterns (generation 4 vs. generations 20-21, respectively) due to regional differences in lung lining fluid volumes. Assuming 0.4% nanoparticle dissolution by mass measured in previous studies predicted peak concentrations of silver ions in cells of 1.06 and 0.89 μg/mL for 20 and 110 nm particles, respectively. Both predicted concentrations are below the measured toxic threshold of 1.7 μg/mL of silver ions in cells from in vitro assessments. Assuming 4% dissolution by mass predicted 10-fold higher silver concentrations in tissues, peaking at 10.6 and 8.9 μg/mL, for 20 and 110 nm nanoparticles respectively, exceeding the observed in vitro toxic threshold and highlighting the importance and sensitivity of dissolution rates. Overall, this approach offers a framework for extrapolating nanotoxicity results from in vitro cell culture systems to human exposures. Aligning appropriate dose metrics from in vitro and in vivo hazard characterizations and human pulmonary doses from occupational exposures are critical components for successful nanoparticle risk assessment and worker protection providing guidance for designing future in vitro studies aimed at relevant human exposures.
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Affiliation(s)
- Jordan Ned Smith
- Biological Sciences Division, Pacific Northwest National Laboratory (PNNL), Richland, WA, 99354, USA
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA
| | - Andrew W. Skinner
- Biological Sciences Division, Pacific Northwest National Laboratory (PNNL), Richland, WA, 99354, USA
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Nickel Nanoparticles Induce the Synthesis of a Tumor-Related Polypeptide in Human Epidermal Keratinocytes. NANOMATERIALS 2020; 10:nano10050992. [PMID: 32455808 PMCID: PMC7279538 DOI: 10.3390/nano10050992] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/14/2020] [Accepted: 05/19/2020] [Indexed: 01/29/2023]
Abstract
Although nickel allergy and carcinogenicity are well known, their molecular mechanisms are still uncertain, thus demanding studies at the molecular level. The nickel carcinogenicity is known to be dependent on the chemical form of nickel, since only certain nickel compounds can enter the cell. This study investigates, for the first time, the cytotoxicity, cellular uptake, and molecular targets of nickel nanoparticles (NiNPs) in human skin cells in comparison with other chemical forms of nickel. The dose-response curve that was obtained for NiNPs in the cytotoxicity assays showed a linear behavior typical of genotoxic carcinogens. The exposure of keratinocytes to NiNPs leads to the release of Ni2+ ions and its accumulation in the cytosol. A 6 kDa nickel-binding molecule was found to be synthesized by cells exposed to NiNPs at a dose corresponding to medium mortality. This molecule was identified to be tumor-related p63-regulated gene 1 protein.
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Radaic A, de Jesus MB, Kapila YL. Bacterial anti-microbial peptides and nano-sized drug delivery systems: The state of the art toward improved bacteriocins. J Control Release 2020; 321:100-118. [PMID: 32035192 DOI: 10.1016/j.jconrel.2020.02.001] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/01/2020] [Accepted: 02/01/2020] [Indexed: 12/27/2022]
Abstract
Antimicrobial peptides (AMP) are molecules consisting of 12-100 amino acids synthesized by certain microbes and released extracellularly to inhibit the growth of other microbes. Among the AMP molecules, bacteriocins are produced by both gram-positive and gram-negative bacterial species and are used to kill or inhibit other prokaryotes in the environment. Due to their broad-spectrum antimicrobial activity, some bacteriocins have the potential of becoming the next generation of antibiotics for use in the crisis of multi antibiotic-resistant bacteria. Recently, bacteriocins have even been used to treat cancer. However, bacteriocins present a few drawbacks, such as sensitivity to proteases, immunogenicity issues, and the development of bacteriocin resistance by pathogenic bacteria. In this regard, nanoscale drug delivery systems (Nano-DDS) have led to the expectation that they will eventually improve the treatment of many diseases by addressing these limitations and improving bacteriocin pharmacokinetics and pharmacodynamics. Thus, combining bacteriocins with nano-DDS may be useful in overcoming these drawbacks and thereby reveal the full potential of bacteriocins. In this review article, we highlight the importance of tailoring nano-DDS to address bacteriocin limitations, the successes and failures of this technology thus far, the challenges that this technology still has to overcome before reaching the market, and future perspectives. Therefore, the purpose of this review is to highlight, categorize, compare and contrast the different nano-DDS described in the literature so far, and compare their effectiveness in order to improve the next generation of bacteriocin nano-sized drug delivery systems (Nano-DDS).
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Affiliation(s)
- Allan Radaic
- Kapila Laboratory, Orofacial Sciences Department, School of Dentistry, University of California, San Francisco (UCSF), San Francisco, CA, USA
| | - Marcelo Bispo de Jesus
- Nano-Cell Interaction Lab., Department of Tissue Biology and Biochemistry, Biology Institute, University of Campinas (UNICAMP), Campinas, SP, Brazil
| | - Yvonne L Kapila
- Kapila Laboratory, Orofacial Sciences Department, School of Dentistry, University of California, San Francisco (UCSF), San Francisco, CA, USA.
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Smith JN, Thomas DG, Jolley H, Kodali VK, Littke MH, Munusamy P, Baer DR, Gaffrey MJ, Thrall BD, Teeguarden JG. All that is silver is not toxic: silver ion and particle kinetics reveals the role of silver ion aging and dosimetry on the toxicity of silver nanoparticles. Part Fibre Toxicol 2018; 15:47. [PMID: 30518385 PMCID: PMC6282353 DOI: 10.1186/s12989-018-0283-z] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 11/20/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND When suspended in cell culture medium, nano-objects composed of soluble metals such as silver can dissolve resulting in ion formation, altered particle properties (e.g. mass, morphology, etc.), and modulated cellular dose. Cultured cells are exposed not just to nanoparticles but to a complex, dynamic mixture of altered nanoparticles, unbound ions, and ion-ligand complexes. Here, three different cell types (RAW 264.7 macrophages and bone marrow derived macrophages from wild-type C57BL/6 J mice and Scavenger Receptor A deficient (SR-A(-/-)) mice) were exposed to 20 and 110 nm silver nanoparticles, and RAW 264.7 cells were exposed to freshly mixed silver ions, aged silver ions (ions incubated in cell culture medium), and ions formed from nanoparticle dissolution. The In Vitro Sedimentation, Diffusion, Dissolution, and Dosimetry Model (ISD3) was used to predict dose metrics for each exposure scenario. RESULTS Silver nanoparticles, freshly mixed ions, and ions from nanoparticle dissolution were toxic, while aged ions were not toxic. Macrophages from SR-A(-/-) mice did not take up 20 nm silver nanoparticles as well as wild-types but demonstrated no differences in silver levels after exposure to 110 nm nanoparticles. Dose response modeling with ISD3 predicted dose metrics suggest that amount of ions in cells and area under the curve (AUC) of ion amount in cells are the most predictive of cell viability after nanoparticle and combined nanoparticle/dissolution-formed-ions exposures, respectively. CONCLUSIONS Results of this study suggest that the unbound silver cation is the ultimate toxicant, and ions formed extracellularly drive toxicity after exposure to nanoparticles. Applying computational modeling (ISD3) to better understand dose metrics for soluble nanoparticles allows for better interpretation of in vitro hazard assessments.
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Affiliation(s)
- Jordan N. Smith
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 93771 USA
| | - Dennis G. Thomas
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Hadley Jolley
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Vamsi K. Kodali
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Matthew H. Littke
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Prabhakaran Munusamy
- The Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Donald R. Baer
- The Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Matthew J. Gaffrey
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Brian D. Thrall
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Justin G. Teeguarden
- Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, WA 99352 USA
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 93771 USA
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Baer DR. The Chameleon Effect: Characterization Challenges Due to the Variability of Nanoparticles and Their Surfaces. Front Chem 2018; 6:145. [PMID: 29868553 PMCID: PMC5949347 DOI: 10.3389/fchem.2018.00145] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/12/2018] [Indexed: 12/12/2022] Open
Abstract
Nanoparticles in a variety of forms are increasing important in fundamental research, technological and medical applications, and environmental or toxicology studies. Physical and chemical drivers that lead to multiple types of particle instabilities complicate both the ability to produce, appropriately characterize, and consistently deliver well-defined particles, frequently leading to inconsistencies, and conflicts in the published literature. This perspective suggests that provenance information, beyond that often recorded or reported, and application of a set of core characterization methods, including a surface sensitive technique, consistently applied at critical times can serve as tools in the effort minimize reproducibility issues.
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Affiliation(s)
- Donald R. Baer
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, United States
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Weldon BA, Park JJ, Hong S, Workman T, Dills R, Lee JH, Griffith WC, Kavanagh TJ, Faustman EM. Using primary organotypic mouse midbrain cultures to examine developmental neurotoxicity of silver nanoparticles across two genetic strains. Toxicol Appl Pharmacol 2018; 354:215-224. [PMID: 29678449 DOI: 10.1016/j.taap.2018.04.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 04/10/2018] [Accepted: 04/13/2018] [Indexed: 11/19/2022]
Abstract
Micromass culture systems have been developed as three-dimensional organotypic in vitro alternatives to test developmental toxicity. We have optimized a murine-based embryonic midbrain micromass system in two genetic strains to evaluate neurodevelopmental effects of gold-cored silver nanoparticles (AgNPs) of differing sizes and coatings-20 nm AgCitrate, 110 nm AgCitrate, and 110 nm AgPVP. AgNPs are increasingly used in consumer, commercial, and medical products for their antimicrobial properties and observations of Ag in adult and fetal brain following in vivo exposures to AgNPs have led to concerns about the potential for AgNPs to elicit adverse effects on neurodevelopment and neurological function. Cytotoxicity was assessed at three time points of development by both nominal dose and by dosimetric dose. Ag dosimetry was assessed in cultures and the gold core component of the AgNPs was used as a tracer for determination of uptake of intact AgNPs and silver dissolution from particles in the culture system. Results by both nominal and dosimetric dose show cell death increased significantly in a dose-dependent manner at later time points (days 15 and 22 in vitro) that coincide with differentiation stages of development in both strains. When assessed by dosimetric dose, cultures were more sensitive to smaller particles, despite less uptake of Ag in smaller particles in both strains.
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Affiliation(s)
- Brittany A Weldon
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Julie Juyoung Park
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Sungwoo Hong
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Tomomi Workman
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Russell Dills
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Ji Hyun Lee
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - William C Griffith
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Terrance J Kavanagh
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Elaine M Faustman
- Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA, USA; Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA.
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Abraham AN, Sharma TK, Bansal V, Shukla R. Phytochemicals as Dynamic Surface Ligands To Control Nanoparticle-Protein Interactions. ACS OMEGA 2018; 3:2220-2229. [PMID: 30023827 PMCID: PMC6045335 DOI: 10.1021/acsomega.7b01878] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/05/2018] [Indexed: 05/05/2023]
Abstract
The rapid formation of the protein corona on to the nanoparticle (NP) surface is the key that confers biological identity to NPs and subsequently dictates their fate both in vitro and in vivo. Despite significant efforts, the inability to control the spontaneous interaction of serum proteins with the administered NPs remains a major constraint in clinical translation of nanomedicines. The ligands present on the NP surface offer promise in controlling their biological interactions; however, their influence on the NP-protein interaction is not well-understood. The current study investigates the potential of phytochemical-capped silver nanoparticles (AgNPs) toward allowing a control over NP interactions with the human serum albumin (HSA), the most abundant protein in the biological fluids. Specifically, we demonstrate the ability of curcumin (Cur) and epigallocatechin-3-gallate (EGCG) to independently act as reducing agents to produce phytochemical-capped AgNPs that show biologically desirable interactions with HSA. The key finding of our study is that the phytochemical-capped AgNPs initially interact with HSA more strongly compared to the citrate-stabilized AgNPs; however, the resultant NP-HSA complexes are less stable in the case of the former, which causes a lesser degree of changes in the protein conformation during interactions. Further, the choice of the phytochemical allows control over NP-HSA interactions, such that Cur- and EGCG-capped AgNPs interacted with HSA in a static versus dynamic manner, respectively. The diversity of the functional groups present in natural phytochemicals and their potential as in situ capping ligands during synthesis offer new opportunities in controlling the interactions of NPs with complex biological fluids, with implications in nanodiagnostics and nanomedicine.
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Affiliation(s)
- Amanda N. Abraham
- Ian Potter NanoBioSensing Facility, NanoBiotechnology
Research Lab
(NBRL), School of Science, and Centre for Advanced Materials & Industrial
Chemistry, School of Science, RMIT University, GPO Box 2476 V, Melbourne, Victoria 3001, Australia
| | - Tarun K. Sharma
- Ian Potter NanoBioSensing Facility, NanoBiotechnology
Research Lab
(NBRL), School of Science, and Centre for Advanced Materials & Industrial
Chemistry, School of Science, RMIT University, GPO Box 2476 V, Melbourne, Victoria 3001, Australia
| | - Vipul Bansal
- Ian Potter NanoBioSensing Facility, NanoBiotechnology
Research Lab
(NBRL), School of Science, and Centre for Advanced Materials & Industrial
Chemistry, School of Science, RMIT University, GPO Box 2476 V, Melbourne, Victoria 3001, Australia
- E-mail: . Phone: +61
3 9925 2121. Fax: +61 3 9925 3747 (V.B.)
| | - Ravi Shukla
- Ian Potter NanoBioSensing Facility, NanoBiotechnology
Research Lab
(NBRL), School of Science, and Centre for Advanced Materials & Industrial
Chemistry, School of Science, RMIT University, GPO Box 2476 V, Melbourne, Victoria 3001, Australia
- E-mail: . Phone: +61 3 992529070. Fax: +61 3 99253747 (R.S.)
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Powell CJ, Werner WSM, Kalbe H, Shard AG, Castner DG. Comparisons of Analytical Approaches for Determining Shell Thicknesses of Core-Shell Nanoparticles by X-ray Photoelectron Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:4073-4082. [PMID: 29887938 PMCID: PMC5990282 DOI: 10.1021/acs.jpcc.7b12070] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We assessed two approaches for determining shell thicknesses of core-shell nanoparticles (NPs) by X-ray photoelectron spectroscopy (XPS). These assessments were based on simulations of photoelectron peak intensities for Au-core/C-shell, C-core/Au-shell, Cu-core/Al-shell, and Al-core/Cu-shell NPs with a wide range of core diameters and shell thicknesses. First, we demonstrated the validity of an empirical equation developed by Shard for determinations of shell thicknesses. Values of shell thicknesses from the Shard equation typically agreed with actual shell thicknesses to better than 10 %. Second, we investigated the magnitudes of elastic-scattering effects on photoelectron peak intensities by performing a similar series of simulations with elastic scattering switched off in our simulation software. Our ratios of the C-shell 1s intensity to the Au-core 4f7/2 intensity with elastic scattering switched off were qualitatively similar to those obtained by Torelli et al. from a model that neglected elastic scattering. With elastic scattering switched on, the C 1s/Au 4f7/2 intensity ratios generally changed by less than 10 %, thereby justifying the neglect of elastic scattering in XPS models that are applied to organic ligands on Au-core NPs. Nevertheless, elastic-scattering effects on peak-intensity ratios were generally much stronger for C-core/Au-shell, Al-core/Cu-shell, and Cu-core/Al-shell NPs, and there were second-order dependences on core diameter and shell thickness.
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Affiliation(s)
- C. J. Powell
- Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370, United States
| | - W. S. M. Werner
- Technical University of Vienna, Institute of Applied Physics, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - H. Kalbe
- Technical University of Vienna, Institute of Applied Physics, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - A. G. Shard
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, United Kingdom
| | - D. G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Chemical Engineering and Bioengineering, University of Washington, Seattle, Washington 98195-1653, United States
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Thomas DG, Smith JN, Thrall BD, Baer DR, Jolley H, Munusamy P, Kodali V, Demokritou P, Cohen J, Teeguarden JG. ISD3: a particokinetic model for predicting the combined effects of particle sedimentation, diffusion and dissolution on cellular dosimetry for in vitro systems. Part Fibre Toxicol 2018; 15:6. [PMID: 29368623 PMCID: PMC5784555 DOI: 10.1186/s12989-018-0243-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 01/16/2018] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND The development of particokinetic models describing the delivery of insoluble or poorly soluble nanoparticles to cells in liquid cell culture systems has improved the basis for dose-response analysis, hazard ranking from high-throughput systems, and now allows for translation of exposures across in vitro and in vivo test systems. Complimentary particokinetic models that address processes controlling delivery of both particles and released ions to cells, and the influence of particle size changes from dissolution on particle delivery for cell-culture systems would help advance our understanding of the role of particles and ion dosimetry on cellular toxicology. We developed ISD3, an extension of our previously published model for insoluble particles, by deriving a specific formulation of the Population Balance Equation for soluble particles. RESULTS ISD3 describes the time, concentration and particle size dependent dissolution of particles, their delivery to cells, and the delivery and uptake of ions to cells in in vitro liquid test systems. We applied the model to calculate the particle and ion dosimetry of nanosilver and silver ions in vitro after calibration of two empirical models, one for particle dissolution and one for ion uptake. Total media ion concentration, particle concentration and total cell-associated silver time-courses were well described by the model, across 2 concentrations of 20 and 110 nm particles. ISD3 was calibrated to dissolution data for 20 nm particles as a function of serum protein concentration, but successfully described the media and cell dosimetry time-course for both particles at all concentrations and time points. We also report the finding that protein content in media affects the initial rate of dissolution and the resulting near-steady state ion concentration in solution for the systems we have studied. CONCLUSIONS By combining experiments and modeling, we were able to quantify the influence of proteins on silver particle solubility, determine the relative amounts of silver ions and particles in exposed cells, and demonstrate the influence of particle size changes resulting from dissolution on particle delivery to cells in culture. ISD3 is modular and can be adapted to new applications by replacing descriptions of dissolution, sedimentation and boundary conditions with those appropriate for particles other than silver.
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Affiliation(s)
- Dennis G. Thomas
- Computational Biology, Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 USA
| | - Jordan N. Smith
- Health Effects and Exposure Science, Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 USA
| | - Brian D. Thrall
- Health Effects and Exposure Science, Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 USA
| | - Donald R. Baer
- Interfacial Sciences and Simulation, Environmental Molecular Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Hadley Jolley
- Health Effects and Exposure Science, Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 USA
| | - Prabhakaran Munusamy
- Interfacial Sciences and Simulation, Environmental Molecular Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352 USA
| | - Vamsi Kodali
- Health Effects and Exposure Science, Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 USA
| | - Philip Demokritou
- Center for Nanotechnology and Nanotoxicology, Department of Environmental Health, Harvard University T. H. Chan School of Public Health, Boston, MA 02115 USA
| | - Joel Cohen
- Center for Nanotechnology and Nanotoxicology, Department of Environmental Health, Harvard University T. H. Chan School of Public Health, Boston, MA 02115 USA
| | - Justin G. Teeguarden
- Health Effects and Exposure Science, Biological Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 USA
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 93771 USA
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Nallanthighal S, Chan C, Murray TM, Mosier AP, Cady NC, Reliene R. Differential effects of silver nanoparticles on DNA damage and DNA repair gene expression in Ogg1-deficient and wild type mice. Nanotoxicology 2017; 11:996-1011. [PMID: 29046123 DOI: 10.1080/17435390.2017.1388863] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Due to extensive use in consumer goods, it is important to understand the genotoxicity of silver nanoparticles (AgNPs) and identify susceptible populations. 8-Oxoguanine DNA glycosylase 1 (OGG1) excises 8-oxo-7,8-dihydro-2-deoxyguanine (8-oxoG), a pro-mutagenic lesion induced by oxidative stress. To understand whether defects in OGG1 is a possible genetic factor increasing an individual's susceptibly to AgNPs, we determined DNA damage, genome rearrangements, and expression of DNA repair genes in Ogg1-deficient and wild type mice exposed orally to 4 mg/kg of citrate-coated AgNPs over a period of 7 d. DNA damage was examined at 3 and 7 d of exposure and 7 and 14 d post-exposure. AgNPs induced 8-oxoG, double strand breaks (DSBs), chromosomal damage, and DNA deletions in both genotypes. However, 8-oxoG was induced earlier in Ogg1-deficient mice and 8-oxoG levels were higher after 7-d treatment and persisted longer after exposure termination. AgNPs downregulated DNA glycosylases Ogg1, Neil1, and Neil2 in wild type mice, but upregulated Myh, Neil1, and Neil2 glycosylases in Ogg1-deficient mice. Neil1 and Neil2 can repair 8-oxoG. Thus, AgNP-mediated downregulation of DNA glycosylases in wild type mice may contribute to genotoxicity, while upregulation thereof in Ogg1-deficient mice could serve as an adaptive response to AgNP-induced DNA damage. However, our data show that Ogg1 is indispensable for the efficient repair of AgNP-induced damage. In summary, citrate-coated AgNPs are genotoxic in both genotypes and Ogg1 deficiency exacerbates the effect. These data suggest that humans with genetic polymorphisms and mutations in OGG1 may have increased susceptibility to AgNP-mediated DNA damage.
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Affiliation(s)
- Sameera Nallanthighal
- a Cancer Research Center , University at Albany, State University of New York , Rensselaer , NY , USA.,b Department of Biomedical Sciences , University at Albany, State University of New York , Albany , NY , USA
| | - Cadia Chan
- a Cancer Research Center , University at Albany, State University of New York , Rensselaer , NY , USA.,c Department of Biomedical Sciences , Queen's University , Kingston , ON , Canada
| | - Thomas M Murray
- d Colleges of Nanoscale Sciences and Engineering , SUNY Polytechnic Institute , Albany , NY , USA
| | - Aaron P Mosier
- d Colleges of Nanoscale Sciences and Engineering , SUNY Polytechnic Institute , Albany , NY , USA
| | - Nathaniel C Cady
- d Colleges of Nanoscale Sciences and Engineering , SUNY Polytechnic Institute , Albany , NY , USA
| | - Ramune Reliene
- a Cancer Research Center , University at Albany, State University of New York , Rensselaer , NY , USA.,e Department of Environmental Health Sciences , University at Albany, State University of New York , Albany , NY , USA
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Shannahan J. The biocorona: a challenge for the biomedical application of nanoparticles. NANOTECHNOLOGY REVIEWS 2017; 6:345-353. [PMID: 29607287 PMCID: PMC5875931 DOI: 10.1515/ntrev-2016-0098] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Formation of the biocorona on the surface of nanoparticles is a significant obstacle for the development of safe and effective nanotechnologies, especially for nanoparticles with biomedical applications. Following introduction into a biological environment, nanoparticles are rapidly coated with biomolecules resulting in formation of the nanoparticle-biocorona. The addition of these biomolecules alters the nanoparticle's physicochemical characteristics, functionality, biodistribution, and toxicity. To synthesize effective nanotherapeutics and to more fully understand possible toxicity following human exposures, it is necessary to elucidate these interactions between the nanoparticle and the biological media resulting in biocorona formation. A thorough understanding of the mechanisms by which the addition of the biocorona governs nanoparticle-cell interactions is also required. Through elucidating the formation and the biological impact of the biocorona, the field of nanotechnology can reach its full potential. This understanding of the biocorona will ultimately allow for more effective laboratory screening of nanoparticles and enhanced biomedical applications. The importance of the nanoparticle-biocorona has been appreciated for a decade; however, there remain numerous future directions for research which are necessary for study. This perspectives article will summarize the unique challenges presented by the nanoparticle-biocorona and avenues of future needed investigation.
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Affiliation(s)
- Jonathan Shannahan
- Corresponding author: Jonathan Shannahan, School of Health Sciences, Purdue University, 550 Stadium Mall Dr. 47907, West Lafayette, Indiana, USA, Tel.: +765-494-2326,
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Aich N, Masud A, Sabo-Attwood T, Plazas-Tuttle J, Saleh NB. Dimensional Variations in Nanohybrids: Property Alterations, Applications, and Considerations for Toxicological Implications. NANOSTRUCTURE SCIENCE AND TECHNOLOGY 2017. [DOI: 10.1007/978-3-319-59662-4_9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Baer DR, Munusamy P, Thrall BD. Provenance information as a tool for addressing engineered nanoparticle reproducibility challenges. Biointerphases 2016; 11:04B401. [PMID: 27936809 PMCID: PMC5074995 DOI: 10.1116/1.4964867] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 09/23/2016] [Accepted: 09/27/2016] [Indexed: 12/11/2022] Open
Abstract
Nanoparticles of various types are of increasing research and technological importance in biological and other applications. Difficulties in the production and delivery of nanoparticles with consistent and well defined properties appear in many forms and have a variety of causes. Among several issues are those associated with incomplete information about the history of particles involved in research studies, including the synthesis method, sample history after synthesis, including time and nature of storage, and the detailed nature of any sample processing or modification. In addition, the tendency of particles to change with time or environmental condition suggests that the time between analysis and application is important and some type of consistency or verification process can be important. The essential history of a set of particles can be identified as provenance information and tells the origin or source of a batch of nano-objects along with information related to handling and any changes that may have taken place since it was originated. A record of sample provenance information for a set of particles can play a useful role in identifying some of the sources and decreasing the extent of particle variability and the lack of reproducibility observed by many researchers.
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Affiliation(s)
- Donald R Baer
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Prabhakaran Munusamy
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
| | - Brian D Thrall
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352
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Powell CJ, Werner WSM, Shard AG, Castner DG. Evaluation of Two Methods for Determining Shell Thicknesses of Core-Shell Nanoparticles by X-ray Photoelectron Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2016; 120:22730-22738. [PMID: 28138350 PMCID: PMC5270650 DOI: 10.1021/acs.jpcc.6b07588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We evaluated two methods for determining shell thicknesses of core-shell nanoparticles (NPs) by X-ray photoelectron spectroscopy (XPS). One of these methods had been developed for determining thicknesses of films on a planar substrate while the other was developed specifically for NPs. Our evaluations were based on simulated Cu 2p3/2 spectra from Cu-core/Cu-shell NPs with a wide range of core diameters and shell thicknesses. Copper was chosen for our tests because elastic-scattering effects for Cu 2p3/2 photoelectrons excited by Al Kα X-rays are known to be strong. Elastic scattering could also be switched off in our simulations so that the two methods could be evaluated in the limit of no elastic scattering. We found that the first method, based on both core and shell photoelectron intensities, was unsatisfactory for all conditions. The second method, based on an empirical equation for NPs developed by Shard, also utilized both core and shell photoelectron intensities and was found to be satisfactory for all conditions. The average deviation between shell thicknesses derived from the Shard equation and the true values was -4.1 % when elastic scattering was switched on and -2.2 % when elastic scattering was switched off. If elastic scattering was switched on, the effective attenuation length for a Cu film on a planar substrate was the appropriate length parameter while the inelastic mean free path was the appropriate parameter when elastic scattering was switched off.
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Affiliation(s)
- C. J. Powell
- Materials Measurement Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370, United States
- Author Information: ., Telephone: (+1) 301-975-2534
| | - W. S. M. Werner
- Technical University of Vienna, Institute of Applied Physics, Wiedner Hauptstrasse 8-10, A-1040 Vienna, Austria
| | - A. G. Shard
- National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, U.K
| | - D. G. Castner
- National ESCA and Surface Analysis Center for Biomedical Problems, Departments of Chemical Engineering and Bioengineering, University of Washington, Seattle, Washington 98195-1653, United States
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Holland NA, Thompson LC, Vidanapathirana AK, Urankar RN, Lust RM, Fennell TR, Wingard CJ. Impact of pulmonary exposure to gold core silver nanoparticles of different size and capping agents on cardiovascular injury. Part Fibre Toxicol 2016; 13:48. [PMID: 27558113 PMCID: PMC4997661 DOI: 10.1186/s12989-016-0159-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 08/16/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The uses of engineered nanomaterials have expanded in biomedical technology and consumer manufacturing. Furthermore, pulmonary exposure to various engineered nanomaterials has, likewise, demonstrated the ability to exacerbate cardiac ischemia reperfusion (I/R) injury. However, the influence of particle size or capping agent remains unclear. In an effort to address these influences we explored response to 2 different size gold core nanosilver particles (AgNP) with two different capping agents at 2 different time points. We hypothesized that a pulmonary exposure to AgNP induces cardiovascular toxicity influenced by inflammation and vascular dysfunction resulting in expansion of cardiac I/R Injury that is sensitive to particle size and the capping agent. METHODS Male Sprague-Dawley rats were exposed to 200 μg of 20 or 110 nm polyvinylprryolidone (PVP) or citrate capped AgNP. One and 7 days following intratracheal instillation serum was analyzed for concentrations of selected cytokines; cardiac I/R injury and isolated coronary artery and aorta segment were assessed for constrictor responses and endothelial dependent relaxation and endothelial independent nitric oxide dependent relaxation. RESULTS AgNP instillation resulted in modest increase in selected serum cytokines with elevations in IL-2, IL-18, and IL-6. Instillation resulted in a derangement of vascular responses to constrictors serotonin or phenylephrine, as well as endothelial dependent relaxations with acetylcholine or endothelial independent relaxations by sodium nitroprusside in a capping and size dependent manner. Exposure to both 20 and 110 nm AgNP resulted in exacerbation cardiac I/R injury 1 day following IT instillation independent of capping agent with 20 nm AgNP inducing marginally greater injury. Seven days following IT instillation the expansion of I/R injury persisted but the greatest injury was associated with exposure to 110 nm PVP capped AgNP resulted in nearly a two-fold larger infarct size compared to naïve. CONCLUSIONS Exposure to AgNP may result in vascular dysfunction, a potentially maladaptive sensitization of the immune system to respond to a secondary insult (e.g., cardiac I/R) which may drive expansion of I/R injury at 1 and 7 days following IT instillation where the extent of injury could be correlated with capping agents and AgNP size.
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Affiliation(s)
- Nathan A. Holland
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, NC 27834 USA
| | - Leslie C. Thompson
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, NC 27834 USA
| | - Achini K. Vidanapathirana
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, NC 27834 USA
| | - Rahkee N. Urankar
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, NC 27834 USA
| | - Robert M. Lust
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, NC 27834 USA
| | - Timothy R. Fennell
- RTI International, Discovery Sciences, Research Triangle Park, NC 27709 USA
| | - Christopher J. Wingard
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, NC 27834 USA
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Wang YC, Engelhard MH, Baer DR, Castner DG. Quantifying the Impact of Nanoparticle Coatings and Nonuniformities on XPS Analysis: Gold/Silver Core-Shell Nanoparticles. Anal Chem 2016; 88:3917-25. [PMID: 26950247 PMCID: PMC4821750 DOI: 10.1021/acs.analchem.6b00100] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Spectral modeling of photoelectrons can serve as a valuable tool when combined with X-ray photoelectron spectroscopy (XPS) analysis. Herein, a new version of the NIST Simulation of Electron Spectra for Surface Analysis (SESSA 2.0) software, capable of directly simulating spherical multilayer NPs, was applied to model citrate stabilized Au/Ag-core/shell nanoparticles (NPs). The NPs were characterized using XPS and scanning transmission electron microscopy (STEM) to determine the composition and morphology of the NPs. The Au/Ag-core/shell NPs were observed to be polydispersed in size, nonspherical, and contain off-centered Au-cores. Using the average NP dimensions determined from STEM analysis, SESSA spectral modeling indicated that washed Au/Ag-core-shell NPs were stabilized with a 0.8 nm layer of sodium citrate and a 0.05 nm (one wash) or 0.025 nm (two wash) layer of adventitious hydrocarbon, but did not fully account for the observed XPS signal from the Au-core. This was addressed by a series of simulations and normalizations to account for contributions of NP nonsphericity and off-centered Au-cores. Both of these nonuniformities reduce the effective Ag-shell thickness, which effect the Au-core photoelectron intensity. The off-centered cores had the greatest impact for the particles in this study. When the contributions from the geometrical nonuniformities are included in the simulations, the SESSA generated elemental compositions that matched the XPS elemental compositions. This work demonstrates how spectral modeling software such as SESSA, when combined with experimental XPS and STEM measurements, advances the ability to quantitatively assess overlayer thicknesses for multilayer core-shell NPs and deal with complex, nonideal geometrical properties.
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Affiliation(s)
| | - Mark H Engelhard
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Box 999, Richland Washington 99352, United States
| | - Donald R Baer
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Box 999, Richland Washington 99352, United States
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Modulation of Human Macrophage Responses to Mycobacterium tuberculosis by Silver Nanoparticles of Different Size and Surface Modification. PLoS One 2015; 10:e0143077. [PMID: 26580078 PMCID: PMC4651328 DOI: 10.1371/journal.pone.0143077] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 10/31/2015] [Indexed: 11/19/2022] Open
Abstract
Exposure to silver nanoparticles (AgNP) used in consumer products carries potential health risks including increased susceptibility to infectious pathogens. Systematic assessments of antimicrobial macrophage immune responses in the context of AgNP exposure are important because uptake of AgNP by macrophages may lead to alterations of innate immune cell functions. In this study we examined the effects of exposure to AgNP with different particle sizes (20 and 110 nm diameters) and surface chemistry (citrate or polyvinlypyrrolidone capping) on cellular toxicity and innate immune responses against Mycobacterium tuberculosis (M.tb) by human monocyte-derived macrophages (MDM). Exposures of MDM to AgNP significantly reduced cellular viability, increased IL8 and decreased IL10 mRNA expression. Exposure of M.tb-infected MDM to AgNP suppressed M.tb-induced expression of IL1B, IL10, and TNFA mRNA. Furthermore, M.tb-induced IL-1β, a cytokine critical for host resistance to M.tb, was inhibited by AgNP but not by carbon black particles indicating that the observed immunosuppressive effects of AgNP are particle specific. Suppressive effects of AgNP on the M.tb-induced host immune responses were in part due to AgNP-mediated interferences with the TLR signaling pathways that culminate in the activation of the transcription factor NF-κB. AgNP exposure suppressed M.tb-induced expression of a subset of NF-κB mediated genes (CSF2, CSF3, IFNG, IL1A, IL1B, IL6, IL10, TNFA, NFKB1A). In addition, AgNP exposure increased the expression of HSPA1A mRNA and the corresponding stress-induced Hsp72 protein. Up-regulation of Hsp72 by AgNP can suppress M.tb-induced NF-κB activation and host immune responses. The observed ability of AgNP to modulate infectious pathogen-induced immune responses has important public health implications.
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Holland NA, Becak DP, Shannahan JH, Brown JM, Carratt SA, Winkle L, Pinkerton KE, Wang CM, Munusamy P, Baer DR, Sumner SJ, Fennell TR, Lust RM, Wingard CJ. Cardiac Ischemia Reperfusion Injury Following Instillation of 20 nm Citrate-capped Nanosilver. ACTA ACUST UNITED AC 2015; 6. [PMID: 26966636 DOI: 10.4172/2157-7439.s6-006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
BACKGROUND Silver nanoparticles (AgNP) have garnered much interest due to their antimicrobial properties, becoming one of the most utilized nano-scale materials. However, any potential evocable cardiovascular injury associated with exposure has not been reported to date. We have previously demonstrated expansion of myocardial infarction after intratracheal (IT) instillation of carbon-based nanomaterials. We hypothesized pulmonary exposure to Ag core AgNP induces a measureable increase in circulating cytokines, expansion of cardiac ischemia-reperfusion (I/R) injury and is associated with depressed coronary constrictor and relaxation responses. Secondarily, we addressed the potential contribution of silver ion release on AgNP toxicity. METHODS Male Sprague-Dawley rats were exposed to 200 μl of 1 mg/ml of 20 nm citrate-capped Ag core AgNP, 0.01, 0.1, 1 mg/ml Silver Acetate (AgAc), or a citrate vehicle by intratracheal (IT) instillation. One and 7 days following IT instillation the lungs were evaluated for inflammation and the presence of silver; serum was analyzed for concentrations of selected cytokines; cardiac I/R injury and coronary artery reactivity were assessed. RESULTS AgNP instillation resulted in modest pulmonary inflammation with detection of silver in lung tissue and alveolar macrophages, elevation of serum cytokines: G-CSF, MIP-1α, IL-1β, IL-2, IL-6, IL-13, IL-10, IL-18, IL-17α, TNFα, and RANTES, expansion of I/R injury and depression of the coronary vessel reactivity at 1 day post IT compared to vehicle treated rats. Silver within lung tissue was persistent at 7 days post IT instillation and was associated with an elevation in cytokines: IL-2, IL-13, and TNFα and expansion of I/R injury. AgAc resulted in a concentration dependent infarct expansion and depressed vascular reactivity without marked pulmonary inflammation or serum cytokine response. CONCLUSIONS Based on these data, IT instillation of AgNP increases circulating levels of several key cytokines, which may contribute to persistent expansion of I/R injury possibly through an impaired vascular responsiveness.
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Affiliation(s)
- N A Holland
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - D P Becak
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - Jonathan H Shannahan
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of Colorado Anschutz Medical Campus, Aurora, USA
| | - J M Brown
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of Colorado Anschutz Medical Campus, Aurora, USA
| | - S A Carratt
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, Davis, California, USA
| | - Lsv Winkle
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, Davis, California, USA
| | - K E Pinkerton
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California at Davis, Davis, California, USA
| | - C M Wang
- Pacific Northwest National Laboratory, EMSL, Richland, USA
| | - P Munusamy
- Pacific Northwest National Laboratory, EMSL, Richland, USA
| | - Don R Baer
- Pacific Northwest National Laboratory, EMSL, Richland, USA
| | - S J Sumner
- RTI International, Discovery Sciences, Research Triangle Park, USA
| | - T R Fennell
- RTI International, Discovery Sciences, Research Triangle Park, USA
| | - R M Lust
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA
| | - C J Wingard
- Department of Physiology, Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA
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