Ritesh K Shukla

ROS-mediated genotoxicity induced by titanium dioxide nanoparticles in human epidermal cells

Titanium dioxide nanoparticles (TiO(2) NPs) are among the top five NPs used in consumer products, paints and pharmaceutical preparations. Since, exposure to such nanoparticles is mainly through the skin and inhalation, the present study was conducted in the human epidermal cells (A431). A mild cytotoxic response of TiO(2) NPs was observed as evident by the MTT and NR uptake assays after 48 h of exposure. However, a statistically significant (p<0.05) induction in the DNA damage was observed by the Fpg-modified Comet assay in cells exposed to 0.8 μg/ml TiO(2) NPs (2.20±0.26 vs. control 1.24±0.04) and higher concentrations for 6 h. A significant (p<0.05) induction in micronucleus formation was also observed at the above concentration (14.67±1.20 vs. control 9.33±1.00). TiO(2) NPs elicited a significant (p<0.05) reduction in glutathione (15.76%) with a concomitant increase in lipid hydroperoxide (60.51%; p<0.05) and reactive oxygen species (ROS) generation (49.2%; p<0.05) after 6h exposure. Our data demonstrate that TiO(2) NPs have a mild cytotoxic potential. However, they induce ROS and oxidative stress leading to oxidative DNA damage and micronucleus formation, a probable mechanism of genotoxicity. This is perhaps the first study on human skin cells demonstrating the cytotoxic and genotoxic potential of TiO(2) NPs.

TiO(2) nanoparticles induce oxidative DNA damage and apoptosis in human liver cells.

Abstract Titanium dioxide nanoparticles (TiO2 NPs), widely used in consumer products, paints, pharmaceutical preparations and so on, have been shown to induce cytotoxicity, genotoxicity and carcinogenic responses in vitro and in vivo. The present study revealed that TiO2 NPs induce significant (p < 0.05) oxidative DNA damage by the Fpg-Comet assay even at 1 µg/ml concentration. A corresponding increase in the micronucleus frequency was also observed. This could be attributed to the reduced glutathione levels with concomitant increase in lipid peroxidation and reactive oxygen species generation. Furthermore, immunoblot analysis revealed an increased expression of p53, BAX, Cyto-c, Apaf-1, caspase-9 and caspase-3 and decreased the level of Bcl-2 thereby indicating that apoptosis induced by TiO2 NPs occurs via the caspase-dependent pathway. This study systematically shows that TiO2 NPs induce DNA damage and cause apoptosis in HepG2 cells even at very low concentrations. Hence the use of such nanoparticles should be carefully monitored.

Surface functionalization of quantum dots for biological applications

Quantum dots are a group of inorganic nanomaterials exhibiting exceptional optical and electronic properties which impart distinct advantages over traditional fluorescent organic dyes in terms of tunable broad excitation and narrow emission spectra, signal brightness, high quantum yield and photo-stability. Aqueous solubility and surface functionalization are the most common problems for QDs employed in biological research. This review addresses the recent research progress made to improve aqueous solubility, functionalization of biomolecules to QD surface and the poorly understood chemistry involved in the steps of bio-functionalization of such nanoparticles.

TiO2 nanoparticles induce DNA double strand breaks and cell cycle arrest in human alveolar cells

TiO2 nanoparticles (NPs) have the second highest global annual production (∼3000 tons) among the metal‐containing NPs. These NPs are used as photocatalysts for bacterial disinfection, and in various other consumer products including sunscreen, food packaging, therapeutics, biosensors, surface cleaning agents, and others. Humans are exposed to these NPs during synthesis (laboratory), manufacture (industry), and use (consumer products, devices, medicines, etc.), as well as through environmental exposures (disposal). Hence, there is great concern regarding the health effects caused by exposure to NPs and, in particular, to TiO2 NPs. In the present study, the genotoxic potential of TiO2 NPs in A549 cells was examined, focusing on their potential to induce ROS, different types of DNA damage, and cell cycle arrest. We show that TiO2 NPs can induce DNA damage and a corresponding increase in micronucleus frequency, as evident from the comet and cytokinesis‐block micronucleus assays. We demonstrate that DNA damage may be attributed to increased oxidative stress and ROS generation. Furthermore, genomic and proteomic analyses showed increased expression of ATM, P53, and CdC‐2 and decreased expression of ATR, H2AX, and Cyclin B1 in A549 cells, suggesting induction of DNA double strand breaks. The occurrence of double strand breaks was correlated with cell cycle arrest in G2/M phase. Overall, the results indicate the potential for genotoxicity following exposure to these TiO2 NPs, suggesting that use should be carefully monitored. Environ. Mol. Mutagen. 56:204–217, 2015.

Titanium dioxide nanoparticle-induced oxidative stress triggers DNA damage and hepatic injury in mice

BACKGROUND The use of metal oxide nanoparticles (titanium dioxide) in consumer and industrial products improves their quality but also underscores the possible adverse effects to human and environmental health. MATERIALS & METHODS Mice were exposed orally for 14 consecutive days and analyzed for alteration in different hepatic enzymes, histopathological changes, oxidative stress, DNA damage, tumor suppressor and proapoptotic protein expression in liver cells. RESULTS We observed a significant alteration in the level of hepatic enzymes and liver histopathology at a dose of 100 mg/kg body weight. Significant oxidative DNA damage was observed in liver cells, which could be attributed to oxidative stress. In addition, the increased expression of p53, BAX, caspase-3 and -9 proteins and decreased expression of antiapoptotic protein Bcl-2, suggest activation of the intrinsic pathway of apoptosis. CONCLUSION High accumulation of titanium dioxide nanoparticles in the liver tissue would cause DNA damage and apoptosis through the intrinsic pathway.

2.45 GHz (Cw) Microwave Irradiation Alters Circadian Organization, Spatial Memory, Dna Structure in the Brain Cells and Blood Cell Counts of Male Mice, Mus Musculus

Present study examines biological efiects of 2.45GHz microwave radiation in Parkes strain mice. Forty-day-old mice were exposed to CW (continuous wave) microwave radiation (2h/day for 30 days). Locomotor activity was recorded on running wheel for 12 days prior to microwave exposure (pre-exposure), 7 days during the flrst week of exposure (short-term exposure) and another 7-day spell during the last week of the 30-day exposure period (long-term exposure). Morris water maze test was performed from 17th to 22nd day of exposure. At the termination of the exposure, blood was processed for hematological parameters, brain for comet assay, epididymis for sperm count and motility and serum for SGOT (serum glutamate oxaloacetate transaminase) and SGPT (serum glutamate

Facile synthesis of nanostructured hydroxyapatite–titania bio-implant scaffolds with different morphologies: their bioactivity and corrosion behaviour

A facile synthesis to fabricate HAp–titania scaffolds with different morphological features has been presented. The hydrothermal approach explored for HAp growth leads to the formation of HAp coating onto titania substrate with distinct morphological features such as cauliflower, urchin, porous nanofibres network, nanorods, etc. under different reaction microenvironments. The XRD analysis done for all HAp–titania scaffold samples revealed the formation of hydroxyapatite phase. Furthermore, the detailed FTIR, SAED and EDS analysis performed confirmed the formation of hydroxyapatite. The addition of H2O2 to the reaction mixture led to the high degree of self-assembly of the formed nanosheets into urchin or consolidated sphere like structures when NaOH or KOH was used in hydrothermal reaction, respectively. The detailed TEM analysis reveals that the formation of such HAp structures takes place by (i) formation of localized corrosion sites on titanium substrate with NaOH/KOH and (ii) the subsequent recrystallization of HAp sol onto the corrosion sites which act as nucleation site. The Tafel plot measurements and MTT assay test indicate that the HAp–titania scaffold samples are corrosion resistance as compared to bare titanium foil and are biocompatible. The structural characterization, growth mechanism, corrosion behaviour in SBF medium and cellular biocompatibility of these scaffold samples are discussed in detail.

TiO2 nanoparticles induced micronucleus formation in human liver (HepG2) cells: comparison of conventional and flow cytometry based methods

Background TiO2 nanoparticles (TiO2 NPs) are extensively used metal oxide NPs in cosmetics, as an additive in pharmaceuticals, food colorant etc. Being widely used NPs, their toxicity assessment studies help in understanding the adverse effects to the humans. It is likely that NPs exposure to the humans can be through different routes but will finally reach the liver. Therefore, an attempt was made to explore the genotoxicity of TiO2 NPs on human liver cells (HepG2).

TiO2 nanoparticles induce cytotoxicity and genotoxicity in human alveolar cells.

Background Engineered nanoparticles (ENPs) such as TiO2 are widely used in products such as cosmetics, clothing, food packaging, drug delivery systems, etc. due to their unique physicochemical properties. This has increased the liklihood of ENP exposure in humans. As the ENPs are having small size and high diffusion coefficient, they can migrate rapidly in the air. Therefore, inhalation is considered to be the primary route of exposure to such ENPs. Hence, in the present study an attempt was made to assess the potential toxicological effects of TiO2 NPs in human alveolar cell line (A549).

BSA coated gold nanoparticles exhibit size dependent interaction with lung cancer (A549) cells

Background Due to high surface to volume ratio and other unique properties, nanomaterials interact within living system (cells, tissues, organisms) significantly different. Therefore, developing a rational basis for investigation and understanding about how these nanomaterials interact with living system is still a fundamental challenge. Further, it has been well documented that nanomaterials get coated by the proteins present in their surrounding thus constructing a “protein corona”. This event also plays a major role in determining the interaction of nanomaterials with cells/tissues. Therefore, to probe this we have chosen BSA coated gold nanoparticles (AuNPs) as a model system to study the interaction with a mammalian lung cell culture model system.