title: Unexpected Thiols Triggering Photoluminescent Enhancement of Cytidine Stabilized Au Nanoclusters for Sensitive Assays of Glutathione Reductase and Its Inhibitors Screening.
abstract: 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.
authors.affiliation: State Key Laboratory of Bioelectronics and School of Biological Science and Medical Engineering, Southeast University , Nanjing, Jiangsu 210096, P. R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Bioelectronics and School of Biological Science and Medical Engineering, Southeast University , Nanjing, Jiangsu 210096, P. R. China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Su
authors.affiliation: State Key Laboratory of Bioelectronics and School of Biological Science and Medical Engineering, Southeast University , Nanjing, Jiangsu 210096, P. R. China.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, Nanjing Medical University , Nanjing, Jiangsu 210029, China.
authors.forename: Junyu
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Pharmacology, Nanjing Medical University , Nanjing, Jiangsu 210029, China.
authors.forename: Danjun
authors.initials: D
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Bioelectronics and School of Biological Science and Medical Engineering, Southeast University , Nanjing, Jiangsu 210096, P. R. China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Wang
mesh_terms: D003562:Cytidine / Q000737:chemistry*; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D005980:Glutathione Reductase / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D049449:Luminescence; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D004791:Enzyme Inhibitors; D013438:Sulfhydryl Compounds; D003562:Cytidine; D006046:Gold; D005980:Glutathione Reductase