In the present study, the toxicity of gold nanoparticles (Au NPs) was evaluated on various trophic organisms. Bacteria, algae, cell line, and mice were used as models representing different trophic levels. Two different sizes (CIT30 and CIT40) and surface-capped (CIT30–polyvinyl pyrrolidone (PVP)-capped) Au NPs were selected. CIT30 Au NP aggregated more rapidly than CIT40 Au NP, while an additional capping of PVP (CIT30–PVP&nbsp;capped Au NP) was found to enhance its stability in sterile lake water medium. Interestingly, all the forms of NPs evaluated were stable in the cell culture medium during the exposure period. Size- and dose-dependent cytotoxicities were observed in both bacteria and algae, with a strong dependence on reactive oxygen species (ROS) generation and lactate dehydrogenase (LDH) release. CIT30–PVP&nbsp;capped Au NP showed a significant decrease in toxicity compared to CIT30 Au NP in bacteria and algae. In the SiHa cell line, dose- and exposure-dependent decline in cell viability were noted for all three types of Au NPs. In mice, the induction of DNA damage was size and dose dependent, and surface functionalization with PVP reduced the toxic effects of CIT30 Au NP. The exposure to CIT30, CIT40, and CIT30–PVP&nbsp;capped Au NPs caused an alteration of the oxidative stress-related endpoints in mice hepatocytes. The toxic effects of the gold nanoparticles were found to vary in diverse test systems, accentuating the importance of size and surface functionalization at different trophic levels. © 2015, Springer-Verlag Berlin Heidelberg.

Amitava Mukherjee

Centre for Nanobiotechnology

Vellore Campus

Chandra Sekaran N

V ISWARYA

J MANIVANNAN

Iswarya V

Manivannan J

A DE

SOUMITRA PAUL

De A

R ROY

Paul S

J B JOHNSON

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

&nbsp;

&nbsp;

VIT University

Environmental Science and Pollution Research

In the current study, the effect of different types of titanium dioxide (TiO 2 ) nanoparticles (NPs) (rutile, anatase, and mixture) was analyzed on Ceriodaphnia dubia in the presence of algae under distinct irradiation conditions such as visible and UV-A. The toxicity experiments were performed in sterile freshwater to mimic the chemical composition of the freshwater system. In addition, the oxidative stress biomarkers such as MDA, catalase, and GSH were analyzed to elucidate the stress induced by the NPs on daphnids. Individually, both rutile and anatase NPs induced similar mortality under both visible and UV-A irradiations at all the test concentrations except 600 and 1200 μM where rutile induced higher mortality under UV-A. Upon visible irradiation, the binary mixture exhibited a synergistic effect at their lower concentration and an additive effect at higher concentrations. In contrast, UV-A irradiation demonstrated the additive effect of mixture except for 1200 μM which elucidated antagonistic effect. Mathematical model confirmed the effects of the binary mixture. The surface interaction between the individual NPs in the form of aggregation played a pivotal role in the induction of specific effects exhibited by the binary mixture. Oxidative stress biomarkers were highly increased upon NPs exposure especially under visible irradiation. These observations elucidated that the irradiation and crystallinity effect of TiO 2 NPs were noted only on certain biomarkers and not on the mortality. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

Toxic effect of different types of titanium dioxide nanoparticles on Ceriodaphnia dubia in a freshwater system

Metal nanoparticles production rate and its applications have raised concerns about their release and toxicity to the aquatic and terrestrial organisms. The primary size of Copper Oxide nanoparticles (CuO NP's) was found to be 114 ± 36 nm using Scanning Electron Microscopy (SEM) and a significant increase in the hydrodynamic diameter of CuO NP was seen within 1 h of interaction. The median lethal concentration (LC50) values obtained from the acute toxicity studies on different life stages of Artemia salina was found to be 61.4, 35, 12.2 and 175.2 mg/L for 1d, 2d, 7d old and adult, respectively. The toxicity associated changes in biochemical markers such as Catalase, Reduced glutathione and Glutathione-S-Transferase were evident. The accumulation of Cu nanoparticles into the gut of Artemia salina was the major reason for toxicity. This study demonstrate the toxicity of CuO NPs to Artemia salina, and the obtained results necessitate the detailed investigation on the possible eco-toxicological implication of these nanomaterials. © 2017 Elsevier B.V.

Environmental Toxicology and Pharmacology

Toxicity and accumulation of Copper oxide (CuO) nanoparticles in different life stages of Artemia salina

Gold nanoparticles (GNPs) are widely used for medical purposes, both in diagnostics as well as drug delivery, and hence are prone to release and distribution in the environment. Thus, we have explored the effects of GNPs with two distinct surface capping (citrate and PVP), and three different sizes (16, 27, and 37&nbsp;nm) at 0.01-, 0.1-, and 1-mg&nbsp;L−1 concentrations on a predominant freshwater alga Scenedesmus obliquus in the sterile freshwater matrix. We have also investigated how an abundant metal ion from freshwater, i.e., Zn2+ ions may modulate the effects of the selected GNPs (40&nbsp;nm, citrate, and PVP capped). Preliminary toxicity results revealed that gold nanoparticles were highly toxic in comparison to zinc ions alone. A significant modulation in the toxicity of Zn ions was not noticed in the presence of GNPs. In contrast, zinc ions minimized the toxicity produced by GNPs (both CIT-37 and PVP-37), despite its individual toxicity. Approximately, about 42, 33, and 25% toxicity reduction was noted at 0.05-, 0.5-, and 5-mg&nbsp;L−1 Zn ions, respectively, for CIT-37 GNPs, while 31% (0.05&nbsp;mg&nbsp;L−1), 24% (0.5&nbsp;mg&nbsp;L−1), and 9% (5&nbsp;mg&nbsp;L−1) of toxicity reduction were noted for PVP-37 GNPs. Maximum toxicity reduction was seen at 0.05&nbsp;mg&nbsp;L−1 of Zn ions. Abbott modeling substantiated antagonistic effects offered by Zn2+ ions on GNPs. Stability and sedimentation data revealed that the addition of zinc ions gradually induced the aggregation of NPs and in turn significantly reduced the toxicity of GNPs. Thus, the naturally existing ions like Zn2+ have an ability to modulate the toxicity of GNPs in a real-world environment scenario

Modulatory effects of Zn2+ ions on the toxicity of citrate- and PVP-capped gold nanoparticles towards freshwater algae, Scenedesmus obliquus

The impact of bio-remediation agent nZVI on environment is still inadequately understood, especially on aquatic food web. The study presented here has therefore considered both chemical (CS) and biological (BS) synthetic origins of nZVI and their effects on both algae and daphnia. The study is unique in its attempt to explore the possibility of trophic transfer from algae to its immediate higher niche (daphnia as the model). An equal weightage of the effects of both CS and BS nZVI on algae and daphnia has been explored here; hence it allows us to compare the capping of nZVI on toxicity. To examine the causes of observed lethality- ROS generation, effects on the activity of oxidative enzymes, membrane damage and biouptake of nZVI was analysed. The overall outcome of CS and BS nZVI on lethality was significantly different in algae and daphnia, where daphnia demonstrated relatively higher sensitivity against CS nZVI. Algae demonstrated considerable differences in CS and BS nZVI toxicity only at higher concentration. This study did not show a probable biomagnification and trophic transfer from algae to daphnia under the experimental conditions even at the highest exposure concentration. The study instigates the importance of trophic transfer to understand the possible biomagnification of nZVI among organisms of different trophic levels and eventually the consequences on environment. © 2016 Elsevier B.V.

Aquatic Toxicology

Toxicity, accumulation, and trophic transfer of chemically and biologically synthesized nano zero valent iron in a two species freshwater food chain

In view of the increasing usage of anatase and rutile crystalline phases of titania NPs in the consumer products, their entry into the aquatic environment may pose a serious risk to the ecosystem. In the present study, the possible toxic impact of anatase and rutile nanoparticles (individually and in binary mixture) was investigated using freshwater microalgae, Chlorella sp. at low exposure concentrations (0.25, 0.5 and 1. mg/L) in freshwater medium under UV irradiation. Reduction of cell viability as well as a reduction in chlorophyll content were observed due to the presence of NPs. An antagonistic effect was noted at certain concentrations of binary mixture such as (0.25, 0.25), (0.25, 0.5), and (0.5, 0.5) mg/L, and an additive effect for the other combinations, (0.25, 1), (0.5, 0.25), (0.5, 1), (1, 0.25), (1, 0.5), and (1, 1) mg/L. The hydrodynamic size analyses in the test medium revealed that rutile NPs were more stable in lake water than the anatase and binary mixtures [at 6. h, the sizes of anatase (1. mg/L), rutile NPs (1. mg/L), and binary mixture (1, 1. mg/L) were 948.83. ±. 35.01. nm, 555.74. ±. 19.93. nm, and 1620.24. ±. 237.87. nm, respectively]. The generation of oxidative stress was found to be strongly dependent on the crystallinity of the nanoparticles. The transmission electron microscopic images revealed damages in the nucleus and cell membrane of algal cells due to the interaction of anatase NPs, whereas rutile NPs were found to cause chloroplast and internal organelle damages. Mis-shaped chloroplasts, lack of nucleus, and starch-pyrenoid complex were noted in binary-treated cells. The findings from the current study may facilitate the environmental risk assessment of titania NPs in an aquatic ecosystem. © 2015 Elsevier B.V.

Combined toxicity of two crystalline phases (anatase and rutile) of Titania nanoparticles towards freshwater microalgae: Chlorella sp

Silver nanoparticles (AgNPs) pose a high risk of exposure to the natural environment owing to their extensive usage in various consumer products. In the present study we attempted to understand the harmful effect of AgNPs at environmentally relevant low concentration levels (≤1. ppm) towards two different freshwater bacterial isolates and their consortium. The standard plate count assay suggested that the AgNPs were toxic towards the fresh water bacterial isolates as well as the consortium, though toxicity was significantly reduced for the cells in the consortium. The oxidative stress assessment and membrane permeability studies corroborated with the toxicity data. The detailed electron microscopic studies suggested the cell degrading potential of the AgNPs, and the FT-IR studies confirmed the involvement of the surface groups in the toxic effects. No significant ion leaching from the AgNPs was observed at the applied concentration levels signifying the dominant role of the particle size, and size distribution in bacterial toxicity. The reduced toxicity for the cells in the consortium than the individual isolates has major significance in further studies on the ecotoxicity of the AgNPs. © 2014 Elsevier Inc.

Ecotoxicology and Environmental Safety

Qualitative toxicity assessment of silver nanoparticles on the fresh water bacterial isolates and consortium at low level of exposure concentration

The aim of the present study was to explore the difference in toxicity mechanism of TiO2 nanoparticles (NPs) at low concentrations (≤1 μg mL-1), in a freshwater bacterial isolate, Bacillus licheniformis, under light (UV-illuminated) and dark (non-illuminated) conditions. Standard plate count and MTT assays showed the dose dependent decrease in the bacterial cell viability. The difference in reduction of cell viability under light (20.7%) and dark conditions (21.3%) was statistically non-significant at 1 μg mL-1 concentration and 2 h interaction period. The fluorescence microscopy of the NP interacted cells (1.0 μg mL-1, 2 h) under light and dark conditions showed the mixture of live and dead cells. A significant dose dependent increase in intracellular ROS generation compared to control was noted. The ROS level after 2 h of interaction was significantly higher under light conditions (7.4 ± 0.13%) as compared to dark conditions (4.35 ± 0.12%). The LDH analyses confirmed a statistically significant increase in membrane permeability under dark conditions compared to the light conditions. The NPs were stable against aggregation in sterilized lake water matrix for a period of 24 h, under both light and dark conditions. However, in the presence of bacterial cells an elevated rate of sedimentation was noted under dark conditions. The electron microscopic (SEM, TEM) observations suggested the concentration buildup of NPs near the plasma membrane leading to internalization. The zeta-potential analysis proved that NP attachment was not charge based. The FTIR studies demonstrated the possible involvement of surface functional groups in the attachment. The concentration of dissolved Ti4+ ions was found to be negligible during the test period. The dominant cytotoxicity mechanism under light conditions was found to be ROS generation, whereas, NP attachment to the cell membrane leading to membrane damage significantly contributed in dark conditions. © 2012 The Royal Society of Chemistry.

Journal	Data powered by TypesetEnvironmental Science and Pollution Research
Publisher	Data powered by TypesetSpringer Verlag
ISSN	0944-1344