Key laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China; Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou, PR China.
Key laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China.
Talanta. 2015 Jun 1;138:144-148. doi: 10.1016/j.talanta.2015.02.012. Epub 2015 Feb 16.
A Hg(2+)-mediated fluorescence turn-on sensor for cysteine (Cys) detection was developed using the nucleic acid minor groove binding dye DAPI. In this work, two fully complementary DNA sequences, a T-rich single-stranded molecule (ssDNA) and an A-rich single-stranded molecule, were employed to constitute consecutive "AT/TA" base pairs, which could strongly enhance the fluorescence of DAPI. In the absence of cysteine, Hg(2+) reacted with T-rich single-stranded DNA and "T-Hg(2+)-T" base pairs formed, this seriously disrupted consecutive AT base pairs. As a result, the fluorescence of DAPI was not increased efficiently. However, considering that cysteine binds strongly to Hg(2+), the structure of the "T-Hg(2+)-T" complexes was destroyed in the presence of cysteine, resulting in the re-formation of consecutive AT base pairs and increased DAPI fluorescence. Obviously, the amount of cysteine could be easily measured based on the enhancement of DAPI fluorescence, and it took only 20 min to complete the whole cysteine-sensing process. Therefore, a label-free fluorescent "turn-on" sensor for the rapid detection of cysteine was designed, and the detection limit of this sensor was as low as 2.4 nM, which was much lower than those of the most of the previously reported cysteine sensors.
基于核酸小沟结合染料 DAPI，开发了一种用于检测半胱氨酸（Cys）的汞（Hg(2+)）介导的荧光开启传感器。在这项工作中，使用了两个完全互补的 DNA 序列，富含 T 的单链分子（ssDNA）和富含 A 的单链分子，它们构成了连续的“AT/TA”碱基对，可强烈增强 DAPI 的荧光。在没有半胱氨酸的情况下，Hg(2+)与富含 T 的单链 DNA 反应并形成“T-Hg(2+)-T”碱基对，这严重破坏了连续的 AT 碱基对。因此，DAPI 的荧光不能有效地增强。然而，考虑到半胱氨酸与 Hg(2+)强烈结合，在半胱氨酸存在的情况下，“T-Hg(2+)-T”复合物的结构被破坏，导致连续的 AT 碱基对重新形成，DAPI 荧光增强。显然，基于 DAPI 荧光的增强，可以很容易地测量半胱氨酸的含量，并且整个半胱氨酸传感过程只需要 20 分钟即可完成。因此，设计了一种用于快速检测半胱氨酸的无标记荧光“开启”传感器，该传感器的检测限低至 2.4 nM，远低于之前报道的大多数半胱氨酸传感器。
