Functionalized Gold Nanoparticles as an Active Layer for Mercury Vapor Detection at Room Temperature

Abstract

Nanomaterials such as gold nanoparticles employed as solid-state sensors have attracted attention in recent years due to their ability to detect poisonous elements in the indoor/outdoor environment. Herein, chemoresistive sensors based on gold nanoparticles (AuNPs) functionalized with mixed thiol ligands were tested as sensing materials. Specifically, the electrical response of gold nanoparticles-based sensors was tested against Hg0 vap, H2S, SO2, NH3, and relative humidity (RH) at room temperature. Gold nanoparticles samples were synthesized by the wet reduction method and then deposited as thin films on suitable interdigitated transducers. Electrical conductivity measurements allowed evaluating a semiconducting behavior of the colloids. A selective and reproducible sensing behavior toward Hg0 vap was observed in the range 0.1–1.0 ng/mL, allowing simple and reliable resistive devices to be obtained. An irreversible interaction mechanism, based on formation of an Au–Hg direct bond, was observed in the case of isolated AuNPs samples. Interconnected AuNPs exhibited a reversible behavior as assessed by Micro Raman, XRD, XPS, AFM, SEM, and UV–vis and FTIR spectroscopies together with DLS measurements. Broadening of the plasmonic band and an increase in the mean particle size upon contact with Hg0 vap was observed. Morphological characterization revealed the formation of aggregates after interaction between Hg0 vap and AuNPs. XRD and Micro Raman measurements collected on the nonexposed and Hg-exposed nanoparticles suggest their structural rearrangement at the surface and formation of an Au–Hg alloy with Hg mechanically trapped within the bulk material. The simple and cost-effective fabrication of these sensors has prospect in the future as nanodevices for real-time outdoor air quality monitoring.

Plasmonic Gold Nanoparticles Stain Hydrogels for the Portable and High-Throughput Monitoring of Mercury Ions

“…On the basis of Au NPs, a series of analysis routes, such as electrochemical, electrochemiluminescent, chemiresistive, field-effect transistor, surface-enhanced Raman scattering, fluorescence, and light-scattering assays, as well as other colorimetric methods, were established through various recognition and response mechanisms (Table S1). − In comparison to their performances of mercury measurements, the developed allochroic hydrogel assay exhibits the merits of simple and rapid operation, ideal sensitivity, high selectivity, and high-throughput characteristics, integrated with the function of mercury enrichment and material reutilization.…”

Construction of Natural Polysaccharide-Based pH-Responsive Gold Nanorods for Combined Photothermal Therapy and Immunotherapy

“…Among them, the peaks at 161.5 and 162.6 eV were attributed to sulfur atoms covalently bound to gold atoms. 48,49 These results confirmed that RRP-MPBA was attached to the surface of the GNRs by the formation of a Au− S bond.…”

Recent Advances in Electrochemical Chitosan-Based Chemosensors and Biosensors: Applications in Food Safety

“…In addition, gold nanomaterials such as nanoparticles, nanoclusters, nanowires, and nanotubes were employed in electrochemical (bio)sensing areas, not only for their high conductivity and compatibility, but also for their high surface-to-volume ratios [38][39][40][41][42][43].…”