Kumud Kant Awasthi

Multi walled carbon nano tubes induced hepatotoxicity in Swiss albino mice

In the present study, multi walled carbon nano tubes (MWCNTs) were synthesized using chemical vapour deposition (CVD) technique. Swiss albino mice were orally administered with single dose of 60 and 100 mg/kg body weight of purified and functionalized MWCNTs suspended in water. The mice were autopsied on 7, 14, 21 and 28 days post exposure. Liver was taken out and part of it fixed in Bouins solution for histopathological examinations. The remaining part was immersed in cold saline, blotted dry, weighed quickly and homogenized in ice cold buffer. The activity of superoxide dismutase (SOD) and catalase (CAT) was immediately measured in the supernatant. The MWCNTs in liver led to pathological changes, including injury to macrophages, cellular swelling, unspecific inflammation, spot necrosis and blood coagulation. Estimation of SOD and CAT showed altered levels in the experimental groups as compared to controls. Therefore, MWCNTs from manufactured and combustion sources in the environment can have adverse effects on human health.

Cytotoxicity, genotoxicity and alteration of cellular antioxidant enzymes in silver nanoparticles exposed CHO cells

The broad applications of silver nanoparticles (Ag NPs) increase human exposure and thus the potential risk associated with their toxicity; therefore, the toxicity of Ag NPs, synthesized by a chemical route was studied using Chinese Hamster Ovary (CHO) cells. A UV-vis absorption maximum at 406 nm confirmed the formation of silver nanoparticles. The average diameter of the silver nanoparticles having spherical shape was found to be about 10.0 ± 1.0 nm by transmission electron microscopy (TEM). For toxicity evaluation, cellular morphology, mitochondrial function (MTT assay), mitochondrial membrane potential, anti-oxidant enzyme assay and comet assay were assessed in CHO cells exposed to various dose concentrations of 25, 50 and 100 μg ml−1 as well as in control cells. Ag NPs caused decreased mitochondrial membrane potential and comparable CAT, SOD, GPx, GST, GR activities as well as total Glutathione level. Comet tail length, tail moment and percent DNA in tail were also found to be increased in a dose dependent manner. In summary, the results suggest that Ag NPs of smaller size at low concentration (25 μg ml−1) cause cytotoxicity by oxidative stress induced apoptosis and damage to DNA and other cellular components.

Green Synthesis of Nanoparticles: An Emerging Phytotechnology

The metallic particles whose size ranges between 1 and 100 nm in any one of the dimensions are termed as nanoparticles (NPs). Nanoparticles pose a great interest to chemists, physicists, biologists, and engineers for the development of new generation nanodevices, electronics, catalysis, chemistry, energy, and medicine. “Green synthesis” refers to the use of green material (i.e., plants) for the synthesis of any material. Nanoparticles can be synthesized by various ways, viz., laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, and microwave processing, which however produce hazardous chemicals as by-product. Green synthesis of NPs is presently becoming popular due to its eco-friendly and cost-effective approach with no use of any toxic chemicals. At the same time, synthesis of NPs through biological methods is not as easy and lots of open challenges are there. Green synthesis of NPs involves the use of water in closed reactors, which is a nontoxic solvent, and applies green techniques like ultrasound and microwave. The reagents used for the synthesis of NPs also include natural compounds such as sugars, vitamins, biodegradable compounds, and microbes. Among these reagents, plant-based materials are the most suitable candidates for large-scale synthesis of NPs. Several plants and their compounds are being used for green synthesis of NPs. This chapter focuses on the range of plants being used for various NP biosynthesis and also gives a view of various applications of NPs in diverse fields.