Unexpected Thiols Triggering Photoluminescent Enhancement of Cytidine Stabilized Au Nanoclusters for Sensitive Assays of Glutathione Reductase and Its Inhibitors Screening

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• 作者：Hui Jiang ; Xiaoqing Su ; Yuanyuan Zhang ; Junyu Zhou ; Danjun Fang ; Xuemei Wang
• 刊名：Analytical Chemistry
• 出版年：2016
• 出版时间：May 3, 2016
• 年：2016
• 卷：88
• 期：9
• 页码：4766-4771
• 全文大小：439K
• 年卷期：0
• ISSN：1520-6882

文摘

The photoluminescence (PL) of nonthiolate ligand capped Au nanoclusters (NCs) is usually quenched by thiols due to the tight adsorption of thiols to the Au surface and formation of larger non-PL species. However, we here report an unexpected PL enhancement of cytidine stabilized Au (AuCyt) NCs triggered by thiols, such as reduced glutathione (GSH) at sub-μM level, while such phenomena have not been observed for Au NCs capped with similar adenosine/cytidine nucleotides. The mass spectroscopic results indicate that this enhancement may be caused by the formation of smaller, but highly fluorescent, Au species etched by thiols. This enables the sensitive detection of GSH from 20 nM to 3 μM, with an ultralow detection limit of 2.0 nM. Moreover, the glutathione reductase (GR) activity can be determined by the initial rate of GSH production, i.e., the maximum PL increasing rate, with a linear range of 0.34–17.0 U/L (1 U means reduction of 1.0 μmol of oxidized glutathione per min at pH 7.6 at 25 °C) and a limit of detection of 0.34 U/L. This method allows the accurate assays of GR in clinical serum samples as well as the rapid screening of GR inhibitors, indicating its promising biomedical applications.