A Highly Sensitive and Selective Colorimetric Hg²⁺ Ion Probe Using Gold Nanoparticles Functionalized with Polyethyleneimine

Abstract

A highly sensitive and selective colorimetric assay for the detection of Hg2+ ions was developed using gold nanoparticles (AuNPs) conjugated with polyethyleneimine (PEI). The Hg2+ ion coordinates with PEI, decreasing the interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry showed that the Hg2+ ion was bound to the nitrogen atoms of the PEI in a bidentate manner (N–Hg2+–N), which resulted in a significant color change from light red to violet due to aggregation. Using this PEI-AuNP probe, determination of Hg2+ ion can be achieved by the naked eye and spectrophotometric methods. Pronounced color change of the PEI-AuNPs in the presence of Hg2+ was optimized at pH 7.0, 50°C, and 300 mM·NaCl concentration. The absorption intensity ratio (A700/A514) was correlated with the Hg2+ concentration in the linear range of 0.003–5.0 μM. The limits of detection were measured to be 1.72, 1.80, 2.00, and 1.95 nM for tap water, pond water, tuna fish, and bovine serum, respectively. Owing to its facile and sensitive nature, this assay method for Hg2+ ions can be applied to the analysis of water and biological samples.

Gold nanoparticles-decorated paper-based sensor for rapid cyanide detection in water

“…This colour change was supported by the appearance of SPR peak at around 522 nm in the UV-vis spectrum as presented in figure 1(a). The observed absorption profile is attributed to the characteristic SPR of monodispersed, spherical AuNPs, as reported in previous literature [37][38][39][40][41][42]. The TEM analysis confirmed that the synthesised AuNPs were almost spherical, with an average particle size of 13.2±2.65 nm (figure 1(b)).…”

Novel Amino-pillar[5]arene as a Fluorescent Probe for Highly Selective Detection of Au3+ Ions

“…Au 3+ ions, a notable heavy metal, have received great attention in chemistry and biology during recent decades and have been widely used in gold plating, environmental studies, anticancer agents, nanomaterials, efficient catalysts, biological sensors, and drug/gene delivery systems based on their unique chemical properties and high biocompatibility. − In addition, these ions have also been developed for application in the jewelry industry . Studies have shown that Au 3+ ions can be used to prepare reduced graphene oxide/Au nanoparticles (NPs), drugs, and catalysts to detect dopamine, ascorbic acid, and uric acid; to treat tuberculosis and rheumatoid arthritis; and to activate carbon–carbon triple bonds. − Although Au 3+ ions have versatile roles in materials science and biological systems, studies have demonstrated that Au 3+ ion-based drugs exhibit potential toxicity at certain concentrations .…”

Recent Trends and Future Perspectives of Emergent Analytical Techniques for Mercury Sensing in Aquatic Environments

“…[70] Recently, advanced colorimetric approaches for Hg 2 + detection have aroused considerable interest. [71][72][73][74] Innovative colorimetric biosensors couple the optical properties of AuÀ NPs through coordinated thymine-mercury-thymine (TÀ Hg 2 + À T), which selectively detects Hg 2 + species. [75,76] For instance, Lee et al [77] established a chip-based scanometric technique that detects Hg 2 + ions through DNA-functionalized AuÀ NPs.…”