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•Synthesis of AgNPs achieved using Malva crispa Linn., leaves extract.•96h LC50 concentration of AgNPs was observed at 142.2μg/l in adult zebrafish.•Cytological changes and ...intrahepatic localization of AgNPs were demonstrated in tissues.•Presence of micronuclei and nuclear abnormalities were observed.•The mRNA expression of stress and immune response related genes were analyzed.
The present study examines the deleterious effect of biologically synthesized silver nanoparticles in adult zebrafish. Silver nanoparticles (AgNPs) used in the study were synthesized by treating AgNO3 with aqueous leaves extract of Malva crispa Linn., a medicinal herb as source of reductants. LC50 concentration of AgNPs at 96h was observed as 142.2μg/l. In order to explore the underlying toxicity mechanisms of AgNPs, half of the LC50 concentration (71.1μg/l) was exposed to adult zebrafish for 14 days. Cytological changes and intrahepatic localization of AgNPs were observed in gills and liver tissues respectively, and the results concluded a possible sign for oxidative stress. In addition to oxidative stress the genotoxic effect was observed in peripheral blood cells like presence of micronuclei, nuclear abnormalities and also loss in cell contact with irregular shape was observed in liver parenchyma cells. Hence to confirm the oxidative stress and genotoxic effects the mRNA expression of stress related (MTF-1, HSP70) and immune response related (TLR4, NFKB, IL1B, CEBP, TRF, TLR22) genes were analyzed in liver tissues and the results clearly concluded that the plant extract mediated synthesis of AgNPs leads to oxidative stress and immunotoxicity in adult zebrafish.
The hydrophobicity of nanoparticles (NPs) is a key property determining environmental fate, biological partitioning and toxicity. However, methods to characterize surface hydrophobicity are not ...uniformly applied to NPs and cannot quantify surface changes in complex environments. Existing methods designed to evaluate the hydrophobicity of bulk solids, chemicals, and proteins have significant limitations when applied to NPs. In this study, we modified and evaluated two methods to determine the hydrophobicity of NPs, hydrophobic interaction chromatography (HIC) and dye adsorption, and compared them to the standard octanol-water partitioning protocol for chemicals. Gold, copper oxide, silica, and amine-functionalized silica NPs were used to evaluate methods based on their applicability to NPs that agglomerate and have surface coatings. The octanol water partitioning and HIC methods both measured Au NPs as hydrophilic, but despite having a small size and stable suspension, NPs could not be fully recovered from the HIC column. For the dye adsorption method, hydrophobic (Rose Bengal) and hydrophilic (Nile Blue) dyes were adsorbed to the NP surface, and linear isotherm parameters were used as a metric for hydrophobicity. CuO was determined to be slightly hydrophilic, while SiO.sub.2 was hydrophilic and Ami-SiO.sub.2 was hydrophobic. The advantages and limitations of each method are discussed, and the dye adsorption method is recommended as the most suitable for application across broad classes of nanomaterials. The dye assay method was further used to measure changes in the surface hydrophobicity of TiO.sub.2 NPs after being suspended in natural water collected from the Alsea Rivers watershed in Oregon. TiO.sub.2 NPs adsorbed Rose Bengal when suspended in ultrapure water, but adsorbed Nile Blue after being incubated in natural water samples, demonstrating a shift from hydrophobic to hydrophilic properties on the outer surface. The dye adsorption method can be applied to characterize surface hydrophobicity of NPs and quantify environmental transformations, potentially improving environmental fate models.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The challenge of optimizing both performance and safety in nanomaterials hinges on our ability to resolve which structural features lead to desired properties. It has been difficult to draw ...meaningful conclusions about biological impacts from many studies of nanomaterials due to the lack of nanomaterial characterization, unknown purity, and/or alteration of the nanomaterials by the biological environment. To investigate the relative influence of core size, surface chemistry, and charge on nanomaterial toxicity, we tested the biological response of whole animals exposed to a matrix of nine structurally diverse, precision-engineered gold nanoparticles (AuNPs) of high purity and known composition. Members of the matrix include three core sizes and four unique surface coatings that include positively and negatively charged headgroups. Mortality, malformations, uptake, and elimination of AuNPs were all dependent on these parameters, showing the need for tightly controlled experimental design and nanomaterial characterization. Results presented herein illustrate the value of an integrated approach to identify design rules that minimize potential hazard.
Encapsulation technology involves entrapping a chemical active ingredient (a.i.) inside a hollow polymeric shell and has been applied to commercial pesticide manufacturing for years to produce ...capsule suspension (CS) formulations with average particle sizes in the micron-scale. The few literature sources that investigate the environmental fate and toxicity to non-target organisms of encapsulated commercially available pesticide products with regard to capsule size report on average sizes between 20 and 50μm. Here, we have identified a CS formulation with an average capsule size of approximately 2μm with some capsules extending into the nanometer scale (~200nm). Determining how carrier size influences toxicity is important to understanding if current pesticide risk assessments are sufficient to protect against products that incorporate encapsulation technology. Here, a commercial pyrethroid CS pesticide with lambda-cyhalothrin (λ-Cy) as the a.i. was separated into two suspensions, a fraction consisting of nano-sized capsules (~250nm) and a fraction of micron-sized capsules (~2200nm) in order to investigate the influence of capsule size on toxicity to embryonic zebrafish, Danio rerio. Toxicity was evaluated 24h after exposure to equivalent amounts of a.i. by the presence and severity of pyrethroid-specific tremors, 14 sublethal developmental impacts and mortality. Fish exposed to greater than 20μg a.i. L−1 technical λ-Cy or formulated product experienced curvature of the body axis, pericardial edema, craniofacial malformations, and mortality. Exposure to the unfractionated formulation, micro fraction, nano fraction and technical a.i. resulted in no significant differences in the occurrence of sublethal impacts or mortality; however, the technical a.i. exposure resulted in significantly less fish experiencing tremors and shorter tremors compared to any of the formulated product exposures. This suggests that the capsule size does not influence the toxic response of the entrapped λ-Cy, but the presence or absence of the capsules does. Testing across other encapsulated products is needed to determine if size does not have influence on toxicity regardless of encapsulation technology.
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•Nanocapsules were detected in a commercial pesticide formulation.•Toxicity of the nanocapsules to zebrafish was compared to that of microcapsules.•The acute toxicity of the nano- and micron-sized capsules was similar.
The embryonic zebrafish model offers the power of whole-animal investigations (e.g., intact organism, functional homeostatic feedback mechanisms, and intercellular signaling) with the convenience of ...cell culture (e.g., cost- and time-efficient, minimal infrastructure, small quantities of nanomaterial solutions required). The model system overcomes many of the current limitations in rapid to high-throughput screening of drugs/compounds and casts a broad net to evaluate integrated system effects rapidly. Additionally, it is an ideal platform to follow up with targeted studies aimed at the mechanisms of toxic action. Exposures are carried out in 96-well plates so minimal solution volumes are required for the assessments. Numerous morphological, developmental, and behavioral endpoints can be evaluated noninvasively due to the transparent nature of the embryos.
There is a pressing need to develop rapid whole animal-based testing assays to assess the potential toxicity of engineered nano-materials. To meet this challenge, the embryonic zebrafish model was ...employed to determine the toxicity of fullerenes. Embryonic zebrafish were exposed to graded concentrations of fullerenes C
60, C
70, and C
60(OH)
24 during early embryogenesis and the resulting morphological and cellular responses were defined. Exposure to 200
μg/L C
60 and C
70 induced a significant increased in malformations, pericardial edema, and mortality; while the response to C
60(OH)
24 exposure was less pronounced at concentrations an order of magnitude higher. Exposure to C
60 induced both necrotic and apoptotic cellular death throughout the embryo. While C
60(OH)
24 induced an increase in embryonic cellular death, it did not induce apoptosis. Our findings concur with results obtained in other models indicating that C
60(OH)
24 is significantly less toxic than C
60. These studies also suggest that the embryonic zebrafish model is well-suited for the rapid assessment of nanomaterial toxicity.
Copper based nanoparticles (NPs) are used extensively in industrial and commercial products as sensors, catalysts, surfactants, antimicrobials, and for other purposes. The high production volume and ...increasing use of copper-based NPs make their ecological risk a concern. Commonly used copper-based NPs are composed of metallic copper or copper oxide (Cu and CuO NPs); however, their environmental toxicity can vary dramatically depending on their physico-chemical properties, such as dissolution, aggregation behavior, and the generation of reactive oxygen species. Here, we investigated the NP dissolution, organismal uptake and aquatic toxicity of Cu and CuO NPs at 0, 0.1, 1, 5 or 10 mg Cu per L using a previously developed multi-species microcosm. This 5 day microcosm assay was comprised of
C. reinhardtti
,
E. coli
,
D. magna
, and
D. rerio
. We hypothesized that Cu and CuO NPs can elicit differential toxicity to the organisms due to alterations in particle dissolution and variations in organismal uptake. The actual concentrations of dissolved Cu released from the NPs were compared to ionic copper controls (CuCl
2
) at the same concentrations to determine the relative contribution of particulate and dissolved Cu on organism uptake and toxicity. We found that both NPs had higher uptake in
D. magna
and zebrafish than equivalent ionic exposures, suggesting that both Cu-based NPs are taken up by organisms. Cu NP exposures significantly inhibited algal growth rate,
D. magna
survival, and zebrafish hatching while exposure to equivalent concentrations of CuCl
2
(dissolved Cu fraction) and CuO NPs did not. This indicates that Cu NPs themselves likely elicited a particle-specific mechanism of toxicity to the test organisms, or a combination effect from ionic Cu and the Cu NPs. Overall, this work was the first study to utilize a small-scale rapid assay designed to evaluate the fate and ecotoxicological impacts of Cu and CuO NPs in a mixed aquatic community.
An efficient and rapid testing paradigm to evaluate the biological uptake, distribution, and ecological risks of Cu based NPs.
Dendrimers are well-defined, polymeric nanomaterials currently being investigated for biomedical applications such as medical imaging, gene therapy, and tissue targeted therapy. Initially, higher ...generation (size) dendrimers were of interest because of their drug carrying capacity. However, increased generation was associated with increased toxicity. The majority of studies exploring dendrimer toxicity have focused on a small range of materials using cell culture methods, with few studies investigating the toxicity across a wide range of materials in vivo. The objective of the present study was to investigate the role of surface charge and generation in dendrimer toxicity using embryonic zebrafish (Danio rerio) as a model vertebrate. Due to the generational and charge effects observed at the cellular level, higher generation cationic dendrimers were hypothesized to be more toxic than lower generation anionic or neutral dendrimers with the same core composition. Polyamidoamine (PAMAM) dendrimers elicited significant morbidity and mortality as generation was decreased. No significant adverse effects were observed from the suite of thiophosphoryl dendrimers studied. Exposure to ≥50 ppm cationic PAMAM dendrimers G3-amine, G4-amine, G5-amine, and G6-amine caused 100% mortality by 24 hours post-fertilization. Cationic PAMAM G6-amine at 250 ppm was found to be statistically more toxic than both neutral PAMAM G6-amidoethanol and anionic PAMAM G6-succinamic acid at the same concentration. The toxicity observed within the suite of varying dendrimers provides evidence that surface charge may be the best indicator of dendrimer toxicity. Dendrimer class and generation are other potential contributors to the toxicity of dendrimers. Further studies are required to better understand the relative role each plays in driving the toxicity of dendrimers. To the best of our knowledge, this is the first in vivo study to address such a broad range of dendrimers.
Driven by major scientific advances in analytical methods, biomonitoring, computation, and a newly articulated vision for a greater impact in public health, the field of exposure science is ...undergoing a rapid transition from a field of observation to a field of prediction. Deployment of an organizational and predictive framework for exposure science analogous to the “systems approaches” used in the biological sciences is a necessary step in this evolution. Here we propose the aggregate exposure pathway (AEP) concept as the natural and complementary companion in the exposure sciences to the adverse outcome pathway (AOP) concept in the toxicological sciences. Aggregate exposure pathways offer an intuitive framework to organize exposure data within individual units of prediction common to the field, setting the stage for exposure forecasting. Looking farther ahead, we envision direct linkages between aggregate exposure pathways and adverse outcome pathways, completing the source to outcome continuum for more meaningful integration of exposure assessment and hazard identification. Together, the two frameworks form and inform a decision-making framework with the flexibility for risk-based, hazard-based, or exposure-based decision making.
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