Double-strand DNA-templated synthesis of copper nanoclusters as novel fluorescence probe for label-free detection of biothiols

Abstract

In this work, we report a simple and sensitive method for the detection of biothiols including glutathione (GSH), cysteine (Cys) and homocysteine (Hcy), using fluorescent copper nanoclusters synthesized by a double-stranded DNA template (DNA-CuNCs) as a probe. The photoluminescence intensity of DNA-CuNCs was found to be quenched effectively with the increase in the concentration of biothiols due to the formation of nonfluorescent coordination complexes between the DNA-CuNCs and biothiols, whereas the fluorescence of DNA-CuNCs was not changed in the presence of other amino acids at a 10-fold higher concentration. Satisfactory detection limits and linear relationships for the detection of GSH, Cys and Hcy were obtained The resulting calibration plots exhibited good linear correlations in the range from 2.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹ for Cys, 2.0 × 10⁻⁶ to 8.0 × 10⁻⁵ mol L⁻¹ for GSH, and 5.0 × 10⁻⁶ to 2.0 × 10⁻⁴ mol L⁻¹ for Hcy. The detection limits of Cys, GSH and Hcy were 2 μmol L⁻¹, 2 μmol L⁻¹ and 5 μmol L⁻¹, respectively. In addition, the method was successfully applied in the detection of biothiols in human plasma samples.