A novel fluorescent sensor for the ratiometric detection of biothiols, such as cysteine (Cys) and glutathione (GSH), was developed. This sensor was based on the system composed of fluorescent silver nanoclusters stabilized by single-stranded DNA (DNA–Ag NCs) and Hg²⁺. The Ag NCs we synthesized had two fluorescence emission peaks, red and green. The red peak was strongly quenched by Hg²⁺ while the green peak showed a concomitant increase in fluorescence intensity in the presence of Hg²⁺. In contrast, when biothiols were added to the DNA–Ag NCs–Hg²⁺ system, there was an increase in the intensity of the red emission peak and a decrease in the intensity of the green emission peak because of the robust Hg–S interaction. By employing the ratio of the DNA–Ag NCs–Hg²⁺ system's red to green fluorescence emission intensity as a function of biothiol concentration, we obtained satisfactory detection limits and linear relationships of Cys and GSH. Cys and GSH were detected at concentrations as low as 1.59 nM and 2.88 nM, respectively. The capability and potential for practical applications of this method were also demonstrated by detecting biothiols in human serum samples.

中文翻译：

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使用DNA模板的银纳米团簇-Hg ²⁺系统 按比例检测生物硫醇

开发了一种新型的荧光传感器，用于按比例检测生物硫醇，例如半胱氨酸（Cys）和谷胱甘肽（GSH）。该传感器基于由单链DNA（DNA-Ag NCs）和Hg ²⁺稳定的荧光银纳米簇组成的系统。我们合成的Ag NCs有两个荧光发射峰，红色和绿色。红色峰被Hg ²⁺强烈淬灭，而绿色峰显示在Hg ²⁺存在下荧光强度随之增加。相反，当将生物硫醇添加到DNA–Ag NCs–Hg ^2+中时在系统中，由于强大的Hg-S相互作用，红色发射峰的强度增加而绿色发射峰的强度减小。通过使用DNA–Ag NCs–Hg ²⁺系统的红色与绿色荧光发射强度之比作为生物硫醇浓度的函数，我们获得了令人满意的Cys和GSH的检出限和线性关系。在低至1.59 nM和2.88 nM的浓度下检测到Cys和GSH。通过检测人血清样品中的生物硫醇，也证明了该方法的实际应用能力和潜力。