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Fluorescence Signal Amplification of Gold Nanoclusters with Silver Ions


The sensing of metal ions (such as Cu2+, Pb2+, Ag+, Fe3+ and Hg2+ etc) with noble metal nanoclusters have been successfully achieved in recent years, and showed advantages in optical stability, hypotoxicity and biocompatibility. Nevertheless, the weak emission intensity and the limited detection scope are the main drawbacks that restrict the practical applications of the nanoclusters. In this study, we first synthesized the water-soluble gold nanocluster capped by bull serum albumin (Au-BSA NC) with intense luminescence, and characterize its structure with transmission electron microscopy (TEM), matrix-assisted laser desorption ionization mass spectra (MALDI-MS), UV-vis absorption spectra, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) spectra etc. It was found that adding Ag+ significantly enhanced the emission intensity of the Au-BSA NC, and resulted in the blueshift of the emission maximum from 620 to 585 nm. The TEM, XPS and DLS (dynamic light scattering) characterizations of the nanoclusters before and after the addition of Ag+ indicate that Ag+ induced the growth of the metal core structure of the Au-BSA NC. In contrast to the remarkably amplified fluorescence signal of Au-BSA NC with Ag+, the addition of all other metal ions (such as Sn2+, Au3+, Fe2+ etc.) results in comparable or weakened fluorescence. Specifically, the fluorescence of Au-BSA was completely quenched by Hg2+, indicating the promising application of Au-BSA as the probe for Hg2+. In this context, Ag+ could be used to enhance the fluorescence signal, and enlarge the detection scope of Hg2+ from μM level to mM scale. In addition, the fluorescence intensity shows excellent linear correlation with -lg[Hg2+], and follows two groups of linear correlations for [Hg2+] ranging from 10 nM→5 μM and 5 μM→0.3 mM.

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Publication details

The article was received on 05 Sep 2018, accepted on 09 Oct 2018 and first published on 09 Oct 2018

Article type: Paper
DOI: 10.1039/C8AY01955J
Citation: Anal. Methods, 2018, Accepted Manuscript
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    Fluorescence Signal Amplification of Gold Nanoclusters with Silver Ions

    W. Jiang, B. Rao, Q. Li, J. Chai, S. Yang, Y. Du, H. Yu and M. Zhu, Anal. Methods, 2018, Accepted Manuscript , DOI: 10.1039/C8AY01955J

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