“…Most of them include chromogenic sensors (Banthia and Samanta 2005), Chemodosimeter-functionalized sensor (Kim et al 2008a, b), fluorescent chemosensor (Zhang et al 2011), atomic absorption spectroscopy (Gonzales et al 2009), inductively coupled plasma mass spectroscopy (Backer et al 2005) and inductively coupled plasma atomic emission spectroscopy (Liu et al 2005 (Zhao et al 2008) such as viruses (Niikura et al 2009), cancerous cells (Midley et al 2008), toxins (Uzawa et al 2008), heavy metals (Barman et al 2014a, b;Fan et al 2009), pesticides Maiti et al 2013;Dasary et al 2009), many inorganic and organic pollutants in water (Daniel et al 2009;Xiao and Yu 2010). The methods of determination rely on their unique size and interparticle distance-dependent absorption spectra and color change of the solution.…”