Oligonucleotide-stabilized fluorescent silver nanoclusters for sensitive detection of biothiols in biological fluids

In this work, we reported a simple and sensitive method to detect biothiols, such as cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), using fluorescent silver nanoclusters (Ag NCs) stabilized by single-stranded DNA (DNA-Ag NCs) as probes. The photoluminescence intensity of DNA-Ag NCs was found to be quenched effectively with the increase of biothiols concentration due to the formed nonfluorescent coordination complex between DNA-Ag NCs and biothiols, resulting in the shift-to-red of emission wavelength. But the fluorescence of DNA-Ag NCs was not changed in the presence of other amino acids at 10-fold higher concentration. Satisfactory detection limits and linear relationships of Cys, GSH and Hcy were obtained, respectively. The resulted plots exhibited good linear relationships in the range from 8.0 x 10(-9) to 1.0 x 10(-7) mol L-1 (R-2 = 0.984) for Cys, 8.0 x 10(-9) to 1.0 x 10(-7) mol L-1 (R-2 = 0.983) for GSH, and 2.0 x 10(-6) to 6.0 x 10(-7) mol L-1 (R-2 = 0.999) for Hcy, respectively; the detection limits of Cys, GSH and Hcy were 4.0 nmol L-1, 4.0 nmol L-1, and 0.2 mu mol L-1, respectively. The method was successfully used for the detection of biothiols in human plasma samples. (C) 2010 Elsevier B.V. All rights reserved.