Dual mechanism-based sensing of mercury using unmodified, heteroepitaxially synthesized silver nanoparticles

Abstract

Mercury and its compounds are widely distributed in the environment and have a significant negative impact on human health. In this paper, we report the development of a rapid and facile method for the detection of mercury ions (Hg 2? ) using heteroepitaxially synthesized unmodified silver nanoparticle-based smart probes using UV-Vis spectrophotometer and also through the naked eye by means of a paper-based sensor strip. The silver nanoparticles were prepared by heteroepitaxial growth method using gold seed nanoparticle of *2.4 nm size as the template. The silver is grown on the seed particles by reducing the silver-ammonia complex using glucose, which resulted in Glu-AgNPs having an average size of 14.65 ± 3.53 nm. The sensing of mercury ions was carried out in aqueous solution and the reaction response was monitored by UV-Vis spectrophotometer. The interaction of Hg 2? with Glu-AgNPs resulted in a significant drop in the absorbance at 402 nm along with a prominent color change (from bright yellow to colorless) and wavelength shift (blue shift). The limit of detection (LOD) of this assay was found to be 100 nM (i.e., 20 ppb) with a good linearity in the concentration range of 100-10 mM. To further ease the detection process and make it field deployable, we attempted to develop a paper-based sensor strip by immobilizing Glu-AgNPs on a paper strip. Upon interaction with mercury solution of varying concentrations, the decoloration of the spots could be observed easily through naked eyes, with the limit of detection under sub-optical conditions being 1 lM.

A combined spectroscopic and ab initio study of the transmetalation of a polyphenol as a potential purification strategy for food additives

“…This phenomena is known as the Mie blue shi, in which the distance between the Ag-NPs become closer owing to the interaction with Hg(II), thus they aggregate with each other and form an Ag-Hg-Ag complex. [54][55][56] As a result of this, Ag/Hg amalgam formation can occur. The aggregated Ag-NPs lose the SPR band (decrease in absorbance) and increase the overall particle size.…”

Gum acacia-based silver nanoparticles as a highly selective and sensitive dual nanosensor for Hg(ii) and fluorescence turn-off sensor for S2− and malachite green detection

“…14 AgNPs are known to be photostable and are less likely to undergo photobleaching, thereby allowing these nanoparticles to be utilized as optical sensors for ultrasensitive mercury detection. [15][16][17] Hazardous sulde ions (S 2À ) have a widespread distribution in both natural and wastewater and are frequently found in industrial areas, such as food processing units, petroleum reneries, and paper and pulp production plants. 18 Sulde in its protonated state becomes even more toxic and poisonous as it turns into bisulde and gaseous hydrogen sulde.…”

Paper-Based Analytical Devices for Colorimetric and Luminescent Detection of Mercury in Waters: An Overview

“…Several mechanisms altering the plasmonic band (changing the color from yellow to colorless) have been proposed for sensing Hg using AgNPs as receptors in PADs [65][66][67][68][69][70][71][72][73]. These mechanisms include changes in both shape and size of AgNPls [65], amalgamation (Hg-Ag) after the reduction of Hg(II) to Hg(0), resulting in the disintegration of AgNPs [66,67,69,70,73] and complexation with capping agent and redox etching due to Hg(II) resulting in amalgamation [68,72].…”

“…A 1 µM concentration could be detected with the naked eye with the µ-PAD. A mechanism based on electrostatic interaction between anionic Glu-AgNPs and cationic Hg and also a redox etching and further amalgam formation was proposed, leading to AgNPs aggregation [68].…”