Label-Free Cysteamine-Capped Silver Nanoparticle-Based Colorimetric Assay for Hg(II) Detection in Water with Subnanomolar Exactitude

Abstract

Precisely probing heavy metal pollutants in water warrants novel methods and materials. To this end, functionalisation of nanoparticles using biologically important substances through a green route is one of the novel aspects for the design of an optical sensor. In this article we report a green preparative strategy for the synthesis of cysteamine stabilized silver nanoparticles (Ag-Nps) in aqueous medium. The water soluble Ag-Nps are found to be highly sensitive and selective for rapid colorimetric detection of Hg(II) ion with a limit of detection (LOD) of 0.273 nM (55 ppt). This system also enables us to detect Hg(II) through naked eye with a LOD of 2.73 nM (0.55 ppb) which is below the WHO permissible limit (10 nM or 2 ppb).Cysteamine undergoes cooperative coordination with the mercury ion leading to spontaneous formation of mercury-cysteamine complex and consequently forms Ag-Hg nano-alloy, which in turn changes the surface plasmon property of the Ag-Nps to allow detection of Hg(II) ion with sub-nanomolar precision. Furthermore, the Ag-Nps were tested for detection of Hg(II) in different real water samples with satisfying recoveries over 96-102 %.

Selective interaction between phytomediated anionic silver nanoparticles and mercury leading to amalgam formation enables highly sensitive, colorimetric and memristor-based detection of mercury

“…5b). The estimated LOD is close to the permissible limit (2 ppb) in drinking water declared by the World Health Organization (WHO) 29 that makes the present assay suitable for analysis of real-life samples. The use of UV-Vis spectroscopy further improved the sensitivity of the method up to 0.1 ppb.…”

Microwave-assisted ultrafast synthesis of silver nanoparticles for detection of Hg2+

“…Mercury is a widespread heavy metal in the environment with high toxicity in all oxidation states [16] and this bioaccumulative species have a severe adverse effect on human health. Solid waste incineration and the combustion of fossil fuels are significant sources of mercury emissions [17].…”

“…A C C E P T E D M A N U S C R I P T 5 as optical probes for Hg 2+ detection through the formation of amalgams, subsequently it brings about the visual signal feedback and UV-vis spectrum response of AgNPs suspension [16,20].…”

“…ACCEPTED MANUSCRIPT 15 phenomena related to a redox reaction between zero-valent silver and Hg 2+ with the standard potential of 0.8 V (Ag + /Ag) and 0.85 V (Hg 2+ /Hg) happened, leading to the formation of Ag−Hg nanoalloy [16,39]. This reversely changed the surface plasmon property of AgNPs and consequently the color of the solution changed.…”

Luminescent turn-on detection of Hg(II) via the quenching of an iridium(III) complex by Hg(II)-mediated silver nanoparticles

“…The characteristic and strong surface plasmon resonance peak was found at around 400 nm when only AgNPs were present 42, 43 . However, as can be seen in Figure S5 (ESI†), the absorption band of AgNPs gradually decreased accompanied by a slight blue shift from 397 to 387 nm upon increasing the concentration of Hg(II) ions.…”