China 
Africa 
Explore chapters and articles related to this topic
Cellular and Molecular Toxicology of Nanoparticles
Published in Vladimir Torchilin, Handbook of Materials for Nanomedicine, 2020
A. Zielińska, D. Santos, J. R. Campos, A. Santini, P. Severino, A. A. M. Shimojo, S. B. Souto, E. B. Souto
The cell can die by apoptosis and/or necrosis [58]. Mitochondrial function plays an important role in the onset of apoptosis since it is the release of proteins present in the mitochondrial membrane that initiate the apoptosis mechanism. One of these molecules is cytochrome C, which when released into the cytosol can lead to the activation of caspases 9, 7 and 3—the protease enzymes playing essential roles in apoptosis and inflammation [22, 55]. Thus, the activity of caspases can be used as a biomarker for apoptosis. There are already kits in the market that evaluate the activity of these enzymes. These kits consist of a peptide susceptible of being cleaved by a caspase. The peptide is marked with a probe that emits fluorescence or changes the color [58]. The condensation of chromatin and fragmentation of the DNA occurs during apoptosis. The detention of these processes can be employed for determining the initiation of apoptosis, during in vitro toxicity tests by using DNA-laddering techniques known as the TNUEL assay. The TUNEL assay detects the DNA fragments by binding to the fragmented ends of the DNA. This bond can be detected by tagging [55]. A substantial amount LDH is leaked into the cell medium after cell damage [9]. The LDH is a biomarker of cell death that it is soluble in the culture medium. Its presence indicates the occurrence of cell damage and can be detected by colorimetry. In the market, there are a few of commercial kits for LDH detection [4, 58].
Methods and Protocols for In Vitro Animal Nanotoxicity Evaluation: A Detailed Review
Published in Vineet Kumar, Nandita Dasgupta, Shivendu Ranjan, Nanotoxicology, 2018
Venkatraman Manickam, Leema George, Amiti Tanny, Rajeeva Lochana, Ranjith Kumar Velusamy, M. Mathan Kumar, Bhavapriya Rajendran, Ramasamy Tamizhselvi
Comet assay is a single cell gel electrophoresis assay which is performed to check the breaks in the DNA strands in eukaryotic cells. In genotoxic evaluation of foreign materials, comet assay is commonly used, and with respect to nanomaterials, it has been extensively used to screen the genotoxicity from titanium dioxide nanoparticles, silver nanoparticles, and magnetic nanoparticles (Figure 12.15). During inflammatory and oxidative stress, as a balancing measure it is common to see cellular cytotoxicity from apoptotic death. DNA laddering assay is an agarose gel electrophoresis based visualization technique in which DNA fragments resulting from apoptosis are visualized. In apoptosis, caspase-activated DNase (CAD) cleaves DNA at inter-nucleosomal linker regions. Resulting DNA fragments of 180–185 bps and higher multiples of them are considered to be a key event during apoptosis. These fragmented DNA can be separated and visualized by using agarose gel electrophoresis, resulting in a characteristic “ladder” pattern.
Preclinical Characterization of Engineered Nanoparticles Intended for Cancer Therapeutics
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Anil K. Patri, Marina A. Dobrovolskaia, Stephan T. Stern, Scott E. McNeil
Apoptosis in mammalian cells can be initiated by four potential pathways: (1) mitochondrial pathway, (2) Death receptor-mediated pathway, (3) ER-mediated pathway, and (4) Granzyme B-mediated pathway.114 Our laboratory has focused on caspase-3 activation in liver and kidney cells as a biomarker of apoptosis, since this a downstream event in all the classical apoptotic signaling pathways and can be measured using a fluorometric protease assay. This assay quantifies caspase-3 activation in vitro by measuring the cleavage of DEVD-7-amino-4-trifluoromethyl coumarin (AFC) to free AFC that emits a yellow-green fluorescence (λmax = 505 nm).115 This initial apoptosis screen can then be followed by additional analysis, as cellular morphology studies using nuclear staining techniques to detect perinuclear chromatin, or agarose gel electrophoresis to detect DNA laddering.116
Environmental transformation and nano-toxicity of engineered nano-particles (ENPs) in aquatic and terrestrial organisms
Published in Critical Reviews in Environmental Science and Technology, 2020
Qumber Abbas, Balal Yousaf, Habib Ullah, Muhammad Ubaid Ali, Yong Sik Ok, Jörg Rinklebe
Comet assay is a widely used technique to assess the damage in DNA structure. Even low exposure concentration of TiO2 ENPs (12.5 mg L−1) reduced the mitotic index and induced the chromosomal aberration in the onion roots (Allium cepa L.). Microscopic techniques along with comet assay confirmed the chromosome breakage, micronuclei formation, sticky and multipolar chromosomes (Pakrashi, Jain, et al., 2014). In addition of comet assay, DNA laddering assay can be used to investigate the DNA internucleosomal cleavage and plants apoptotic cell death upon interaction with CNTs (Ghosh, Bhadra, Adegoke, Bandyopadhyay, & Mukherjee, 2015). These studies indicate that ENPs upon interaction with plants induced cyto-genotoxic effects and regulate the expression levels of different genes involved in physiological and biochemical processes (Table 2). However, further in-depth studies are required in order to understand the severity of DNA damage, mechanism of plants recovery from DNA damage, and intergenerational transfer of traits to next progeny under the influence of nano-genotoxicity. Moreover, proteomic, and metabolomic studies should also be conducted to understand the complex ENPs interaction with different plant species.
Pharmacological properties of dicyanidoaurate(I)-based complexes: characterization and single crystal X-ray analysis
Published in Journal of Coordination Chemistry, 2019
Ahmet Karadağ, Ali Aydin, Şaban Tekin, Hüseyin Akbaş, Süreyya Dede
The morphological variations of the cells were evaluated considering the application time and dose. As shown in Supplementary information Figure S9, clear morphological alterations were screened in the treated cells due to the dose values compared to the vehicle. Morphological changes of 1, 2, and 3 were seen in cells exposed to test complexes for 24 h. In morphology, the compounds clearly caused significant changes suggesting apoptotic cell characteristics such as cell shrinkage and rounding, and other changes such as surface membrane changes and detachment from the culture plate (Supplementary information Figure S9). The compounds also provoked distortion of cell surfaces in the flask. HeLa, HT29, and C6 cells were clumped together loosening their plasticities and fibroblastic appearances. It should also be highlighted that the quality and number of cells in the flask surface were reduced by compounds. These findings were close to those of former studies by Karadağ et al., Korkmaz et al., Aydın et al. and Tekin et al. [19–24]. Thus, the morphology of the cell lines treated with test complexes clearly exhibited the antiproliferative and sustainable cytotoxic effect of these complexes. Moreover, the outcomes of DNA laddering assay and TUNEL assay suggest that these complexes may disrupt cell proliferation via activating apoptosis.