Achieving Ultrasensitive Point-of-Care Assay for Mercury Ions with a Triple-Mode Strategy Based on the Mercury-Triggered Dual-Enzyme Mimetic Activities of Au/WO₃ Hierarchical Hollow Nanoflowers

Abstract

The exploration of new strategies for portable detection of mercury ions with high sensitivity and selectivity is of great value for biochemical and environmental analyses. Herein, a straightforward, convenient, label-free, and portable sensing platform based on a Au nanoparticle (NP)-decorated WO 3 hollow nanoflower was constructed for the sensitive and selective detection of Hg(II) with a pressure, temperature, and colorimetric triple-signal readout. The resulting Au/WO 3 hollow nanoflowers (Au/WO 3 HNFs) could efficaciously impede the aggregation of Au NPs, thus significantly improving their catalytic activity and stability. The sensing mechanism of this new strategy using pressure as a signal readout was based on the mercury-triggered catalase mimetic activity of Au/ WO 3 HNFs. In the presence of the model analyte Hg(II), H 2 O 2 in the detection system was decomposed to O 2 fleetly, resulting in a detectable pressure signal. Accordingly, the quantification of Hg(II) was facilely realized based on the pressure changes, and the detection limit could reach as low as 0.224 nM. In addition, colorimetric and photothermal detection of Hg(II) using the Au/WO 3 HNFs based on their mercury-stimulated peroxidase mimetic activity was also investigated, and the detection limits were calculated to be 78 nM and 0.22 μM for colorimetric and photothermal methods, respectively. Hence, this nanosensor can even achieve multimode determination of Hg(II) with the concept of point-of-care testing (POCT). Furthermore, the proposed multimode sensing platform also displayed satisfactory sensing performance for the Hg(II) assay in actual water samples. This promising strategy may provide novel insights on the fabrication of a multimode POCT platform for sensitive, selective, and accurate detection of heavy metal ions.

Composites of Fe3O4, Ag, and Au Nanoparticles for Dye Degradation and Selective Detection of Glutathione

“…In the case of Fe 3 O 4 /Au, three signal peaks at 38.3, 44.3, and 64.5° were ascribed to the (111), (200), and (220) crystal planes of the Au. While for Fe 3 O 4 /Ag Au, the peaks at 38.2, 44.3, and 64.6° were indexed to the (111), (200), and (220) planes of the Ag (JCPDS no: 04-0783) and Au (JCPDS no: 04-0784) cubic phases. In the XRD pattern, no other diffraction peaks were found, indicating the successful synthesis of these highly purified magnetic nanomaterials.…”

Colorimetric mercury detection with enhanced sensitivity using magnetic-Au hybrid nanoparticles

“…The enzymatic activity of Au nanoparticles is enhanced by the formation of an amalgam with Hg 2+ ; thus, several studies explore the use of Au hybrid nanoparticles for Hg 2+ detection. 26,28,30,45 To examine the possibility of using Mag-Au hybrid nanoparticles for Hg 2+ ion detection, the peroxidase-like activity of the Mag-Au hybrid nanoparticles was compared in the presence and absence of Hg 2+ (Fig. 2a).…”

“…For example, Au interacts strongly with Hg 2+ ions forming an HgAu alloy (amalgam), which leads to a remarkable enhancement of the peroxidase-like activity of Au nanoparticles (Au NPs). [26][27][28][29][30][31][32] The strong chelating interaction of Hg 2+ with Ag 2 S@graphene oxide also provides an excellent synergistic catalytic effect. 33 Mercuric cations downregulate the enzymatic activities of Pt, Se, SnTe, CuS, and Co 3 O 4 nanoparticles.…”

Logic-Gates of Gas Pressure for Portable, Intelligent and Multiple Analysis of Metal Ions

“…Gas pressure, as a common physical parameter, has attracted increasing attention for developing portable biosensing and bioanalysis. In recent years, gas pressure-based biosensing has been successfully developed for detecting various kinds of targets, such as nucleic acid, protein, cell, and heavy metal ion. − These advances solidly confirmed the outstanding versatility and reliability of gas pressure-based biosensing. So, it has the potential to integrate gas pressure output with logic gates for portable and intelligent biosensing.…”