Generated Mercury(I) as a Peroxidase-like Activity Modulator via Stimulating the Expression of Active Sites of Silver Nanoparticles for Environmental Hg²⁺ Detection

Abstract

Developing a peroxidase-like activity modulator to accurately regulate peroxidase-like activity has always been the primary challenge to be addressed. External stimulation can effectively modulate the electronic structure of metal-centered active sites, which optimizes the chemical reaction path and changes the peroxidase-like activity. Herein, in a weak acidic environment (pH = 6.0), we found that the electron transfer may occur between silver nanoparticles (Ag NPs) anchored on the surface of reduced graphene oxide/poly(ethylene glycol) (rGO/ PEG) nanosheets and added mercury(II) (Hg 2+ ), which can induce the formation of mercurous ions (Hg(I), Hg 2 2+ ). Hg(I) with regulatory catalytic performance can stimulate the expression of the active sites of Ag NPs via optimizing the electronic structure so that the adsorbed H 2 O 2 molecules can efficiently produce reactive oxygen intermediates ( • OH and • O 2 − ) and be stabilized on the surface of Ag NPs. Meanwhile, density functional theory (DFT) calculations showed that the generated Hg(I) significantly reduced the Gibbs free energy of the chemical reaction and provided a pathway for electron transfer, which effectively enhanced the peroxidase-like activity. Based on this finding, a visual colorimetric sensor was constructed to detect Hg 2+ with a detection limit of 19.7 nM in the range of 0.02−5.0 μM. Finally, we confirmed that the developed rGO/PEG/Ag nanohybrids can quantitatively detect Hg 2+ in the environment. This method is reliable and has potential advantages in the environmental application field.

Mercury Ion-Responsive Coalescence of Silver Nanoparticles on a Silica Nanoparticle Core for Surface-Enhanced Raman Scattering Sensing

“…These advantages of amalgam have recently been actively applied to colorimetric detection involving the catalytic reaction of dye molecules. 11,12 One of the important phenomena in amalgamation of noble metal NPs is that the formation of nanoalloys can lead to morphological changes in NPs, altering their localized surface plasmon resonance (LSPR) characteristics. 13 By taking advantage of this effect on plasmonic features, various methods for mercuric ion (Hg 2+ ) detection through amalgamation have been proposed using noble metal NPs and hybrid nanocomposites.…”

“…The series of morphological changes entailed by the amalgamation influence the plasmonic features, which significantly depend on their nanostructure and composition. , The amalgams exhibit properties that are significantly different from those of the original materials, such as enhanced nanozyme characteristics. These advantages of amalgam have recently been actively applied to colorimetric detection involving the catalytic reaction of dye molecules. , One of the important phenomena in amalgamation of noble metal NPs is that the formation of nanoalloys can lead to morphological changes in NPs, altering their localized surface plasmon resonance (LSPR) characteristics . By taking advantage of this effect on plasmonic features, various methods for mercuric ion (Hg 2+ ) detection through amalgamation have been proposed using noble metal NPs and hybrid nanocomposites. − Most of the methods are based on colorimetric analysis by tuning and shifting the LSPR band in the absorption spectrum.…”