A label-free colorimetric detection of lead ions by controlling the ligand shells of gold nanoparticles

Toward selective, sensitive, and discriminative detection of Hg2+ and Cd2+via pH-modulated surface chemistry of glutathione-capped gold nanoclusters

“…As illustrated in Figure 2B and 2C, other metal ions (Mg 2+ , Ca 2+ , Zn 2+ , Al 3+ , Ni 2+ , Co 2+ , etc.) 48 These results suggest that GSH-Au NCs have good selectivity toward Hg 2+ and Cd 2+ at appropriate pH and could thus be used for simple fluorimetric detection of Hg 2+ and Cd 2+ separately with two opposing readout modes. Meanwhile, the fluorescence response toward Hg 2+ or Cd 2+ was only slightly affected by the coexistence of most of these metal ions, even though the tested concentrations of some ions are much higher than that of Hg 2+ and Cd 2+ (Figure 3).…”

Plasmonic‐Coupling‐Based Sensing by the Assembly and Disassembly of Dipycolylamine‐Tagged Gold Nanoparticles Induced by Complexing with Cations and Anions

“…In addition to these applications, other strategies could also be employed with the AuNP@DPA‐based recognition system to enhance its selectivity and sensitivity 23. For example, using buffer solution can adjust the ionic strength and/or pH for improved sensitivity20 and the addition of specific ligands to analytes can induce the preferential formation of coordination complexes, thus masking the effects of interfering ions 28, 47…”

“…Ordered assemblies of AuNPs result in interparticle surface plasmon resonance (SPR) coupling due to reduced average interparticle spacing; they also exhibit color changes6, 7 and red‐shifted characteristic LSPR bands in their UV‐vis extinction spectra 8–10. Such SPR coupling‐based color changes of noble metal nanoparticles have been considered versatile tools for developing sensitive and selective molecular recognition systems, with colorimetric sensing investigated for application in biological assays11–16 and metal ion detection 17–20…”

Gold nanoflowers based colorimetric detection of Hg2+ and Pb2+ ions

“…Hence, to circumvent the drawbacks of analytical techniques, a variety of chemosensors [10][11][12][13][14] has been developed to detect Pb 2+ . Contrary to fluorescence enhancement/quenching methods [10][11][12][13][14], colorimetric methods [15][16][17][18][19][20][21] are appealing because they can be directly read out with the naked eye. In this context gold nanoparticles based colorimetric sensor for Pb 2+ and Hg 2+ is a promising alternative because Au nanoparticles have a tremendous extinction coefficient, which is several orders of magnitude greater than the extinction coefficients of traditional organic chromophores [9].…”

“…Additionally, the surface plasmon resonance band of Au nanoparticles is highly sensitive to the distance between nanoparticles. Though, in literature highly selective detection of Pb 2+ and Hg 2+ ions using modified Au nanoparticles has been accomplished [10][11][12][13][14][15][16][17][18][19][20][21] but most of the studies required modification of Au surface. In this study, we present a simple colorimetric assay for Pb 2+ and Hg 2+ ions without any modification of the Au nanoparticles surface.…”