Facile Preparation of High-Quantum-Yield Gold Nanoclusters: Application to Probing Mercuric Ions and Biothiols
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- 作者：Heng-Chia Chang ; Ying-Feng Chang ; Nien-Chu Fan ; Ja-an Annie Ho
- 刊名：ACS Applied Materials & Interfaces
- 出版年：2014
- 出版时间：November 12, 2014
- 年：2014
- 卷：6
- 期：21
- 页码：18824-18831
- 全文大小：408K
- ISSN：1944-8252
文摘
This paper describes an eco-friendly, one-pot strategy for the synthesis of water-soluble, high-quantum-yield gold nanoclusters (AuNCs) stabilized with 11-mercaptoundecanoic acid (MUA) on their surfaces. The as-prepared ultrasmall MUA鈥揂uNCs (1.9 nm) exhibited a quantum yield (QY) of 13%, higher than those of most previously described thiol-protected AuNCs. We applied these MUA鈥揂uNCs as a versatile probe to develop a fluorescence 鈥渢urn-off鈥?assay for sensing Hg2+ ions as well as a fluorescence 鈥渢urn-on鈥?assay for sensing biothiols. The former assay operated through aggregation-induced fluorescence quenching upon interaction of the MUA鈥揂uNCs with Hg2+ ions in a buffer containing 2,6-pyridinedicarboxylic acid (PDCA); this probe provided high sensitivity and remarkable selectivity over other selected metal ions with a limit of detection (LOD) for Hg2+ ions of 450 pM and linearity from 2 to 50 nM. In the latter assay for biothiols [i.e., cysteine (Cys), homocysteine (Hcy), glutathione (GSH)], the fluorescence of the Hg2+鈥揗UA鈥揂uNCs complexes was turned on because the affinity of Hg2+ ions toward the SH group of the biothiols was greater than that toward the COOH groups of the MUA units on the surface of the AuNCs. This assay provided good linearity for the tested biothiols, ranging from 10 to 100 nM for Cys, from 10 to 100 nM for Hcy, and from 5 to 75 nM for GSH, with LODs of 5.4, 4.2, and 2.1 nM, respectively. In addition, these environmentally and biologically friendly AuNC probes tested satisfactorily against interference from a range of amino acids.