Facile Synthesis of Water-Soluble Fluorescent Silver Nanoclusters and Hg^II Sensing

Abstract

A single step facile synthesis of highly emissive, water-soluble, fluorescent Ag nanoclusters has been reported using a small molecule, dihydrolipoic acid. These clusters were characterized using ultraviolet/visible (UV/vis) spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD) studies. Mass spectrometric analysis shows the presence of a few atoms in nanoclusters containing only Ag 4 and Ag 5 . The reported fluorescent Ag nanoclusters show excellent optical properties, including narrow emission profile, larger Stokes shift (more than 200 nm), and good photostability. Interestingly, these nanoclusters also exhibit semiconducting property. Moreover, as-prepared fluorescent Ag nanoclusters have been utilized as an indicator for selective and ultrasensitive detection of highly toxic Hg II ions in water, even at subnanomolar concentrations.

The Influence of Parameters of Ink-Jet Printing on Photoluminescence Properties of Nanophotonic Labels Based on Ag Nanoparticles for Smart Packaging

“…The absorption spectrum in Figure 2 shows several sharp transition bands with maxima at 327, 435, and 497 nm combined with a shallow absorbance onset that starts around 700 nm. The spectra obtained are similar to those presented in [24].…”

“…The Ag nanoparticles (NPs) were synthesized following a modification of the method published by Adhikari and Banerjee [24]. -Lipoic acid (6 × 10 −2 M) and 8,2 ml of demi water were placed into a 20 ml flask.…”

A facile synthesis of highly stable and luminescent Ag clusters: a steady-state and time-resolved spectroscopy study

“…The absorption spectrum Ag clusters stabilized by dihydrolipoic acid (DHLA) were observed to exhibit similar absorption features. 17 Several other research groups synthesized Ag clusters with various sizes using different capping agents, and for all clusters they found very similar absorption features in the UV and visible region of the spectrum. 35,36,42,43,48 In agreement with these results, the particular structural features of the absorption spectra may be associated with Ag clusters that consist of 5 to 9 atoms.…”

Recent developments on nanomaterials-based optical sensors for Hg2+ detection

“…For the Ag NPs based sensing assay which is similar to the Au NCs-based sensing principle, Ag NCs stabilized with oligonucleotide [95], dBSA [96], GSH [97,98], DHLA [99] were synthesized and used as fluorescent probes for the selective and sensitive detection of Hg 2+ , based on the fluorescence quenching of Ag NCs due to the 5d 10 (Hg 2+ )-4d 10 (Ag + ) metallophilic interaction [96,97] or the aggregation of Ag NCs induced by Hg 2+ [98,99]. The detection limit could reach 0.1 nM [98,99].…”

“…The detection limit could reach 0.1 nM [98,99]. Besides the "turn-off " Hg 2+ sensors, Deng et al [100] established a "turn-on" fluorescence sensor for Hg 2+ using the Hg 2+ -mediated T-T formation to strengthen the DNA duplexes and influence the configuration of Ag NCs-forming sequence.…”