State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, People's Republic of China.
Anal Chem. 2010 Feb 15;82(4):1515-20. doi: 10.1021/ac902638v.
The lead ion (Pb(2+)) has been proven to induce a conformational change of K(+)-stabilized G-quadruplex DNAzyme and inhibit the peroxidase-like activity [Li, T.; Wang, E.; Dong, S. J. Am. Chem. Soc. 2009, 131, 15082-15083]. This provides a rationale for utilizing Pb(2+)-induced allosteric G-quadruplex DNAzyme to probe aqueous Pb(2+). Here, we choose a common G-quadruplex DNAzyme named PS2.M to develop a novel Pb(2+) sensor with two detection means: colorimetry and chemiluminescence (CL). In the presence of K(+), PS2.M (with hemin as a cofactor) exhibits a superior DNAzyme activity and effectively catalyzes the H(2)O(2)-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) or luminol, which results in a color change or generates CL emission. Upon the addition of Pb(2+), K(+)-stabilized PS2.M is induced to convert to the Pb(2+)-stabilized structure with higher stability but lower DNAzyme activity, which is reflected by an obvious increase in DNA melting temperature but a sharp decrease in readout signal. This allows us to utilize PS2.M for quantitative analysis of aqueous Pb(2+) using the ABTS-H(2)O(2) colorimetric system and luminol-H(2)O(2) CL system. In each case, the readout signal is linearly dependent on the logarithm of Pb(2+) concentration within a certain range. Nevertheless, two sensing systems provide different sensitivity for Pb(2+) analysis. With colorimetry, Pb(2+) can be detected at a level of 32 nM (approximately 7 ppb), whereas the detection limit of Pb(2+) is 1 nM (0.2 ppb) when utilizing the CL method. In addition to high sensitivity, the above sensing systems exhibit good selectivity for Pb(2+) over other metal ions. These results demonstrate the facility and effectivity of our introduced DNAzyme-based sensor for quantitative Pb(2+) analysis.
铅离子（Pb(2+)）已被证明能诱导 K(+)稳定的 G-四链体 DNA 酶构象变化，并抑制过氧化物酶样活性[Li, T.; Wang, E.; Dong, S. J. Am. Chem. Soc. 2009, 131, 15082-15083]。这为利用 Pb(2+)诱导的变构 G-四链体 DNA 酶来探测水溶液中的 Pb(2+)提供了依据。在这里，我们选择一种常见的 G-四链体 DNA 酶 PS2.M 来开发一种新的 Pb(2+)传感器，该传感器具有两种检测手段：比色法和化学发光法（CL）。在 K(+)存在下，PS2.M（以血红素为辅助因子）表现出优异的 DNA 酶活性，并有效催化 H(2)O(2)介导的 2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）或鲁米诺的氧化，导致颜色变化或产生 CL 发射。当加入 Pb(2+)时，K(+)稳定的 PS2.M 被诱导转化为 Pb(2+)稳定的结构，其稳定性更高，但 DNA 酶活性更低，这反映在 DNA 熔解温度明显增加，但读出信号急剧下降。这使我们能够利用 PS2.M 通过 ABTS-H(2)O(2)比色系统和鲁米诺-H(2)O(2) CL 系统对水溶液中的 Pb(2+)进行定量分析。在每种情况下，读出信号与 Pb(2+)浓度的对数在一定范围内呈线性关系。然而，两种传感系统对 Pb(2+)分析提供了不同的灵敏度。通过比色法，可以在 32 nM（约 7 ppb）的水平检测 Pb(2+)，而当使用 CL 法时，Pb(2+)的检测限为 1 nM（0.2 ppb）。除了高灵敏度外，上述传感系统对 Pb(2+)与其他金属离子具有良好的选择性。这些结果表明，我们引入的基于 DNA 酶的传感器用于定量分析 Pb(2+)具有很高的实用性和有效性。
