The overall work depicted the toxicity of silver nanoparticle to marine organism
Along with the extensive application of silver nanoparticles (AgNPs), growing concerns have been paid to their potential risks on aquatic organisms. The present study investigated the potential risk of AgNPs on marine fish, including both waterborne and dietary AgNPs exposures. In the waterborne exposure, we found that fast aggregation of AgNPs would proceed immediately in the high saline medium (>15 psu), while the addition of Tween 20 (20 μM ) could well stabilize AgNPs against aggregation even in the 30 psu salinity medium. Uptake rate constants (ku) of AgNPs were less than half of the soluble Ag at low salinities (1 and 5 psu), while limited bioavailability of c-AgNPs was observed at high salinities (15 and 30 psu). However, the Tween 20 stabilized AgNPs (t-AgNPs) were accumulated by medaka at comparable rate as the soluble Ag, indicating the importance of dispersion for bioavailability of AgNPs in a highly ionic environment. In the dietary exposure, we found that the assimilation efficiency (AE) of Ag (AgNO3, 20 and 80 nm AgNPs) from contaminated brine shrimp in the medaka was quite low (<6%) and independent of food Ag (20 nm AgNPs) concentration. However, even this small amount of assimilated Ag (from AgNPs contaminated food) generated toxic effects (e.g., inhibition of Na+/K+-ATPase and SOD activity, reduction of total body length and WC) on medaka during the 28-day chronic dietary exposure. The overall study highlighted the potential of AgNPs-contaminated food by generating toxicity to marine fish, while less impact was likely from the waterborne exposure in the high saline environment.
Abstract: With the extensive applications of metallic-based nanomaterials (MNs), concerns are growing of their potential impact on aquatic organisms. Unlike traditional metal pollutants, MNs have different surface properties and compositions, which may modify their impact on aquatic environments as well as their bioavailability to aquatic organisms. Kinetic processes of MNs, such as dissolution, stabilization, aggregation, and sedimentation, are important in determining their bioavailability and subsequent toxicity to aquatic organisms. Among all of the physicochemical kinetics, the dissolution of MNs attracts the most attention, due to their potential toxicity generated by dissolved ions. This review summarizes the dissolution behavior of three common MNs, i.e., ZnO nanoparticles (ZnO-NPs), Ag nanoparticles (Ag-NPs), and TiO2 nanoparticles (TiO2-NPs), in toxicological studies. A kinetic model was developed to evaluate the contribution of dissolved ion on the total MN accumulation. Finally, toxicological data of the MNs to algae, zooplankton, and fish are summarized and interpreted based on their kinetics. Different dissolution rates were observed for ZnO-NPs, Ag-NPs, and TiO2-NPs, and their solubility also varied during different toxicological studies, leading to a variable but increasing waterborne ion concentration during exposure. The bioavailability of these MNs and corresponding ions also varied for different aquatic organisms (e.g., algae, zooplankton, and fish). Specifically, the MNs appeared to be more bioavailable to daphnids, rendering a minor contribution of ion during short-term exposure. Generally, dissolved ion contributed partially to toxicity of ZnO-NPs and Ag-NPs, while the toxicity of TiO2-NPs was mainly due to the generated reactive oxygen species (ROS). Additionally, the role of dissolved ion in both MN bioaccumulation and toxicity intensified during chronic exposure as a result of dissolution, thus it is critical to monitor the dissolution of MNs in toxicological studies. This review emphasizes the importance of integrating physicochemical kinetics and uptake kinetics in evaluating the bioavailability and toxicity of both MNs and dissolved ions.
Pub.: 08 Aug '14, Pinned: 27 Jul '17
Abstract: Concerns for the potential risks of silver nanoparticles (AgNPs) to aquatic organisms have increased. The present study investigated the trophic transfer of AgNPs from brine shrimp (Artemia salina) nauplii to marine medaka. We found that the aggregated AgNPs (20 and 80 nm) and well dispersed 80-nm AgNPs (stabilized by 20 μM Tween 20) could be readily accumulated by brine shrimp, while far less well-dispersed 20-nm AgNPs were accumulated. The assimilation efficiency (AE) of AgNPs in medaka fed AgNPs-contaminated brine shrimp was low (<6%), resulting in a low trophic transfer efficiency (0.01-0.04) after 28 days of chronic dietary exposure. However, such low bioavailability of dietary AgNPs could inhibit the whole-body Na+/K+-ATPase and superoxide dismutase (SOD) activity in the fish within the first 2 weeks of exposure. Significant (p<0.05, two-way ANOVA) inhibition occurred in the high AgNPs-contaminated brine shrimp treatment over 28 days of chronic exposure. Furthermore, reduced growth and water content percentage were also observed in fish fed high dosages of AgNPs-contaminated brine shrimp. Our study highlighted the potential of trophically available AgNPs in bringing toxicity to the marine fish.
Pub.: 18 Jun '14, Pinned: 27 Jul '17
Abstract: With increasing use of silver nanoparticles (AgNPs), concerns about their potential deleterious effects on aquatic ecosystems have increased. Most previous studies have focused on the toxicity of AgNPs while their bioavailability has been seldom investigated. The present study examined the effects of salinity on the aggregation kinetics as well as the bioavailability of commercial 80-nm citrate-coated AgNPs (c-AgNPs) in the presence or absence of a nonionic surfactant (Tween 20) to marine medaka (Oryzias melastigma). In addition, the uptake of soluble Ag was quantified for comparison and for deducting the uptake of soluble Ag during AgNP exposure by applying a biokinetic model. The authors found that the addition of Tween 20 immediately slowed down the process of aggregation of AgNPs, and an elevated amount of Tween 20 (20 µM) kept AgNPs well dispersed, even in the 30-psu salinity medium. Uptake rate constants (ku ) of AgNPs were less than half the soluble Ag at low salinities (1 psu and 5 psu), while limited bioavailability of c-AgNPs was observed at high salinities (15 psu and 30 psu). However, the Tween 20-stabilized AgNPs (t-AgNPs) were accumulated by medaka at comparable rates as the soluble Ag, indicating the importance of dispersion for bioavailability of AgNPs in a highly ionic environment. The present study provided the first insight of the bioavailability of AgNPs to fish in a high-ionic environment. More studies are needed to gain a full understanding of bioavailability of AgNPs in marine environments.
Pub.: 28 Jan '14, Pinned: 27 Jul '17
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