Carboxymethylagarose-AuNPs generated through green route for selective detection of Hg2+ in aqueous medium with a blue shift.

We report here a facile, rapid, cost-effective method via a green route for the selective detection of Hg(2+) in aqueous media. In this study carboxymethylagarose (CMA) is used to generate gold nanoparticles and subsequently to act as a stabilizer for the CMA-functionalized gold nanoparticles (CMA-AuNPs). The resulting CMA-AuNPs was characterized by UV-visible, X-ray diffraction, transmission electron microscopy (TEM), dynamic light scattering (DLS), atomic force microscopy (AFM) and zeta potential measurements. Zeta potential value (∼ -73 mv) of CMA-AuNPs in the aqueous medium shows its higher stability. When CMA-AuNPs were exposed to an aqueous Hg(2+), a blue shift for its localized surface plasmon resonance absorbance (LSPR) band is observed along with significant colour change of the solution. The probe enables to detect Hg(2+) in the range of 0.01-100 ppm even in spiked lake water samples. This study offers a sustainable and eco-friendly route for selective detection of Hg(2+) in aqueous solution and may find potential application towards water purification.