Biofabrication of Silver Nanoparticles for Selective and
Sensitive Colorimetric Detection of Hg(II) Ions

The current study explored a green, simple, selective and cost-effective method for the detection of
Hg2+ ions in the aqueous medium using silver nanoparticles (AgNPs) synthesized from marine
macroalgae Sargassum duplicatum. The biosynthesized AgNPs were further characterized by using
UV-visible spectroscopy, FTIR, HR-TEM, SAED and XRD techniques. The synthesized AgNPs were
almost spherical in shape and polydisperse in nature. Due to the intense SPR absorption band, the
biosynthesized AgNPs solution is seen as dark brown colour. In the presence of Hg2+, the brown coloured
AgNPs solution becomes colourless coupled with the disappearance of absorption maxima at 419 nm.
The selectivity and sensitivity of AgNPs towards Hg2+ were also investigated and the minimum detection
limit was found to be 0.1 μM. Furthermore, a test strip technique for the rapid detection of Hg2+ was
also devised. Thus, the biogenic AgNPs are expected to be a promising candidate for developing
low-cost Hg2+ sensors.