In view of increasing commercial applications of metal oxide nanoparticles their toxicity assessment becomes important. Alumina (Al2O 3) nanoparticles have wide range of applications in industrial as well as personal care products. In the absence of prior report on toxicological impact of alumina nanoparticles to microalgae, the principal objective of this study was to demonstrate the effect of the nanoparticles on microalgae isolated from aquatic environment (Scenedesmus sp. and Chlorella sp.). The growth inhibitory effect of alumina nanoparticles was observed for both the species (72 h EC50 value, 45.4 mg/L for Chlorella sp.; 39.35 mg/L for Scenedesmus sp.). Bulk alumina also showed toxicity though to a lesser extent (72 h EC50 value, 110.2 mg/L for Chlorella sp.; 100.4 mg/L for Scenedesmus sp.). A clear decrease in chlorophyll content was observed in the treated cells compared to the untreated ones, more effect being notable in the case of nanoparticles. Preliminary results based on FT-IR studies, optical and scanning electron microscopic images suggest interaction of the nanoparticles with the cell surface. © 2011 Springer Science+Business Media B.V.

Chandra Sekaran N

Centre for Nanobiotechnology

Vellore Campus

Amitava Mukherjee

Sadiq I.M

Pakrashi S

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.

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VIT University

Journal of Nanoparticle Research

There has recently been an increase in the usage of TiO2 nanoparticles (NPs). P25 TiO2 NPs, a mixture of anatase and rutile phase in 3:1 ratio, are generally used for photocatalytic applications because both phases exhibit a synergistic effect on the photocatalytic activity of the TiO2 NPs. In the present study, increased toxicity of UVA-pre-irradiated P25 TiO2 NPs on freshwater algae Scenedesmus obliquus was assessed under visible light and dark exposure conditions at actual low concentrations (0.3, 3 and 35 μM of Ti). Photocatalytic property of P25 TiO2 NPs caused disaggregation of UVA-pre-irradiated NPs, thus significantly decreasing the mean hydrodynamic diameter (MHD) (188.74 ± 0.54 nm) than that of non-irradiated NPs (232.26 ± 0.44). This decrease in diameter of UVA-pre-irradiated NPs may increase its biological activity towards algal samples. All concentrations of pre-irradiated NPs, under both light and dark conditions, showed a significantly lesser cell viability (p

Environmental Science and Pollution Research

UVΑ pre-irradiation to P25 titanium dioxide nanoparticles enhanced its toxicity towards freshwater algae Scenedesmus obliquus

This study assesses the temporal changes in the physico-chemical behaviour of titanium dioxide nanoparticles (anatase and rutile phase) for a period of 120 h at environmentally relevant concentration of 1,000 µg/L, and the consequent impact on the microalgae population in a fresh water microcosm. The mean hydrodynamic size analysis in the medium revealed the differences in the aggregation behaviour of the two crystalline types of particles within first 12 h exposure before they had reached the micron size range. While the short term exposure (120 h) showed an immediate effect on the resident microalgae in the microcosm with respect to control, there were no significant differences in ecotoxicity effects of rutile and anatase phases of titania. The long term (90 days) exposure demonstrated a gradual recovery of the resident algal population. Summarizing the observations, the nanosized particles at low concentration may not retain the toxic potential for longer exposure time in a microcosm presumably owing to the complexity prevalent in the natural systems. © 2014, The National Academy of Sciences, India.

Proceedings of the National Academy of Sciences, India Section B: Biological Sciences

A Temporal Study on the Effects of TiO2 Nanoparticles in a Fresh Water Microcosm

Cytotoxicity, genotoxicity, and biochemical effects were evaluated in the plants Allium cepa, Nicotiana tabacum, and Vicia faba following exposure to ZnO nanoparticles (np; diameter, ∼85&nbsp;nm). In the root meristems of Allium cepa cells, we observed loss of membrane integrity, increased chromosome aberrations, micronucleus formation, DNA strand breaks, and cell-cycle arrest at the G2/M checkpoint. In Vicia faba and Nicotiana tabacum, we observed increased intracellular ROS production, lipid peroxidation, and activities of some antioxidant enzymes. TEM images revealed gross morphological alterations and internalization of the np. Our findings provide evidence of ZnO np toxicity, characterized by deregulation of components of ROS-antioxidant machinery, leading to DNA damage, cell-cycle arrest, and cell death. These plants, especially Allium cepa, are reliable systems for assessment of np toxicology. © 2016 Elsevier B.V.

Mutation Research - Genetic Toxicology and Environmental Mutagenesis

Effects of ZnO nanoparticles in plants: Cytotoxicity, genotoxicity, deregulation of antioxidant defenses, and cell-cycle arrest

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.

Aquatic Toxicology

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

The commercial usage of Al2O3 nanoparticles (Al2O3 NPs) has gone up significantly in the recent times, enhancing the risk of environmental contamination with these agents and their consequent adverse effects on living systems. The current study has been designed to evaluate the cytogenetic potential of Al2O3 NPs in Allium cepa (root tip cells) at a range of exposure concentrations (0.01, 0.1, 1, 10, and 100 μg/mL), their uptake/internalization profile, and the oxidative stress generated. We noted a dose-dependent decrease in themitotic index (42 to 28 %) and an increase in the number of chromosomal aberrations. Various chromosomal aberrations, e.g. sticky, multipolar and laggard chromosomes, chromosomal breaks, and the formation of binucleate cells, were observed by optical, fluorescence, and confocal laser scanning microscopy. FT-IR analysis demonstrated the surface chemical interaction between the nanoparticles and root tip cells. The biouptake of Al2O3 in particulate form led to reactive oxygen species generation, which in turn probably contributed to the induction of chromosomal aberrations. © Springer-Verlag Berlin Heidelberg 2015.

Cytotoxicity of aluminum oxide nanoparticles on Allium cepa root tipâ€”effects of oxidative stress generation and biouptake

Metal oxide nanoparticles (NPs) are known to possess strong antimicrobial properties. Aluminum oxide NPs have wide-range applications in industrial as well as personal care products. In the absence of prior reports on the antimicrobial properties of alumina NPs for a wide concentration range, the principal objective of the present work was to study the growth-inhibitory effect of alumina NPs over a wide concentration range (10-1000 μg/mL) on an environmentally relevant gram-negative model microorganism, Escherichia coli. The mean diameter of the NPs was determined to be 179 nm in aqueous dispersion used for this study, and surface area was determined to be 21.23 m2/g. The concentration of 1000 μg/mL was found to be moderately inhibitory for bacteria. Almost negligible dependence of growth rate on the concentration of the NPs was observed. The extracellular protein content was found to be slightly lower in case of cells interacting with 1000 μg/mL alumina than the uninteracted control cells. Fourier transform-infrared studies established differences in structure between interacted and uninteracted cells. Alumina NPs showed a mild growth-inhibitory effect, only at very high concentrations, which might be due to surface charge interactions between the particles and cells. Free-radical scavenging properties of the particles might have prevented cell wall disruption and drastic antimicrobial action. This laboratory-scale study suggests that alumina NPs may only exhibit mild toxicity toward microorganisms in the environment. From the Clinical Editor: Metal oxide NPs, inluding aluminum oxide NPs, are known to possess strong antimicrobial properties. The study demonstrated a mild to moderate growth-inhibitory effect of alumina NPs over a wide concentration range (10-1000 μg/mL) on Escherichia coli. Almost negligible dependence on the concentration was observed. © 2009 Elsevier Inc. All rights reserved.

Journal	Data powered by TypesetJournal of Nanoparticle Research
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ISSN	1388-0764
Open Access	0