Acknowledgements

interaction of host and guest. But one of the best indirect As(III) sensors is reported in recent time. Sourav et al. reported one norbornene-derived rhodamine B, which is capable of detecting As(III) in aqueous medium up to 200 nM concentration [70]. Here, the main dominating factor is the oxidation of As(III) to As(V) in the presence of potassium iodate and concentrated HCl. During this oxidation procedure, iodine is liberated which coordinates with sensing molecule Nor-Rh, which leads to the colorimetric as well as fluorescence change. The effectiveness of this work is that the polymeric material of Nor-Rh can be used to make paper strip which will help to detect As(III) in real environmental samples. A cartoon representation is given in Figure 9 to demonstrate the color change of polymer-coated paper strip with and

Figure 9. Cartoon representation to demonstrate change in color of PNor-Rh-coated paper strip in the absence and

In summary, though few reports are available for efficient detection of arsenic in aqueous medium with high sensitivity, research community continuously tries to develop sensory assay for 'on-field' application, with a tremendous impact in detection of arsenic in environmental

Arsenic, having a high reactivity with cellular contents, can have diverse and deleterious effects on the cells. One of the important players of arsenic-induced toxicity is the generation of ROS, which can lead to DNA damage and lipid peroxidation. Another important effect is the arsenic exposure that causes the depletion of methyl groups in cellular milieu. Hypomethylation of promoter regions can lead to overexpression of genes which play a key role in cell proliferation, differentiation and apoptosis. As mentioned earlier, DNA hypomethylation upregulates receptors like ER-α making the cells more sensitive towards endogenous steroids. Arsenic is reported to activate PKC which activates MAPK pathway leading to the activation of various transcription factors like AP-1. AP-1 is considered as a crucial player in regulation of cell proliferation, differentiation and apoptosis. Arsenic effects extracellular matrix through upregulation of MMPs resulting in degradation of extracellular matrix having consequences in cellular migration, angiogenesis, proliferation and apoptosis. The biological effects of arsenic are so diverse that multiple

without As(III).

presence of As(III).

74 Arsenic - Analytical and Toxicological Studies

6. Conclusion

samples with ease and real-life application.

The study of mechanisms of arsenic-induced toxicity with special emphasis on arsenic-binding proteins is supported by the Indian Institute of Science Education and Research Kolkata (IISER-K), India. The success of this work has largely depended on the contribution and devotion of the PhD students, project students and many collaborators whose names are listed in the references.
