Role of silver nanoparticles and silver nanoclusters for the detection and removal of Hg(ii)

Abstract

Silver metal, being a 3d transition metal in group 11 in the periodic table, is widely used in material science for its distinguished plasmonic properties. Nanoparticles (NPs) and nanoclusters (NCs) are widely used in sensing applications having a surface plasmon band and emissive properties, respectively. Mercury is one of the detrimental toxins and threats to various ecosystems. The distinction between nanoparticles and nanoclusters, the utility and toxicity of heavy metal mercury, fluorometric and colorimetric approaches to the recognition of mercury ions with NPs and NCs, the mechanism of detection, spot detection, and natural water sample analyses were illustrated in detail in this review article. Moreover, the sensing platform and analyte (Hg²⁺) fate were described for substantiating the mechanism. It was observed that NCs are mostly utilized for fluorometric approaches, while NPs are mostly employed for colorimetric approaches. Fluorometric detection is mainly quenching-based. However, sensing with enhancement was found in a few reports. Adulteration of other metals with silver particles often modifies the sensing platform.

Fig. 1. Techniques for extracting gold using Hg in artisanal mining processes.

Fig. 2. Miners in Sulawesi, Indonesia, add one kilogram of mercury to each ball mill when kids play nearby the operational area. Reproduced with permission from ref. , copyright 2024, J. Clean. Prod.

Fig. 3. (A) Optimized structures of neutral AgnHg complexes, n ≤ 6. The symmetry point group is indicated. (B) Optimized structures of anionic AgnHg complexes, n ≤ 6. The symmetry point group is indicated. (C) Optimized structures of cationic AgnHg complexes, n ≤ 6. The symmetry point group is indicated. Reproduced with permission from ref. , copyright 2024, Chem. Phys. Lett.

Fig. 4. Fluorescence-based sensing of mercury with AgNCs, with different capping agents.

Fig. 5. Mechanism of fluorometric detection of Hg²⁺ with AgNCs.

Fig. 6. Synthesis protocol for the preparation of water-soluble fluorescent AgNCs. Reproduced with permission from ref. , copyright 2024, J. Environ. Chem. Eng.

Fig. 7. (A) Synthesis of DNA13 passivated Ag clusters, (B) fluorescence spectra after the addition of Hg²⁺, (C) linear detection range, and (D) effect of competing metal ions. Reproduced with permission from ref. , copyright 2024, Biosens Bioelectron.

Fig. 8. Quenching of fluorescence with Hg²⁺via DNA-AgNPs. Reproduced with permission from ref. , copyright 2024, Anal. Chem.

Fig. 9. Colorimetric-based sensing of mercury with AgNPs, with different capping agents.

Fig. 10. (a) Digital image and (b) UV-vis spectra of synthetic AgNPs containing various transition-metal ions. Reproduced with permission from ref. , copyright 2024, Sens. Actuators B: Chem.

Fig. 11. Sensing of mercury with tyrosine-stabilized AgNPs involving the Tyndall effect. Reproduced with permission from ref. , copyright 2024, Sens. Actuators B: Chem.

Fig. 12. TEM images of the AgNPs solution (0.075 nM) mixed with 300 nM MSO in the (A) absence or (B) presence of 500 nM Hg²⁺ after the addition of 60 mM NaCl. Reproduced with permission from ref. , copyright 2024, ACS Appl. Mater. Interfaces.

Fig. 13. (I) Formation of Ag–Hg amalgam after the treatment of Hg²⁺ to 3-MPS capped AgNPs; (II) (a) UV-visible spectra and (b) DLS spectra of 3-MPS capped AgNPs with the addition of Hg²⁺; (III) TEM image (a) before and (b) after the addition of Hg²⁺; (IV) (a) STEM image before addition of Hg²⁺, (b) STEM image after addition of Hg²⁺, (c) EDS mapping before addition of Hg²⁺, and (d) EDS mapping after addition of Hg²⁺; (V) XPS spectra for the element mercury after the addition of Hg²⁺ at two different concentrations. Reproduced with permission from ref. , copyright 2024, J. Phys. Chem. C.

Fig. 14. Bimetallic gold silver giant clusters with strong emissive properties for versatile applications. Reproduced with permission from ref. , copyright 2024, Langmuir.

Mamta Sahu

Mainak Ganguly

Priyanka Sharma