AbstractAn isothermal colorimetric method is described for amplified detection of the CaMV 35S promoter sequence in genetically modified organism (GMO). It is based on (a) target DNA-triggered unlabeled molecular beacon (UMB) termini binding, and (b) exonuclease III (Exo III)-assisted target recycling, and (c) hemin/G-quadruplex (DNAzyme) based signal amplification. The specific binding of target to the G-quadruplex sequence-locked UMB triggers the digestion of Exo III. This, in turn, releases an active G-quadruplex segment and target DNA for successive hybridization and cleavage. The Exo III impellent recycling of targets produces numerous G-quadruplex sequences. These further associate with hemin to form DNAzymes and hence will catalyze H2O2-mediated oxidation of the chromogenic enzyme substrate ABTS2− causing the formation of a green colored product. This finding enables a sensitive colorimetric determination of GMO DNA (at an analytical wavelength of 420 nm) at concentrations as low as 0.23 nM. By taking advantage of isothermal incubation, this method does not require sophisticated equipment or complicated syntheses. Analyses can be performed within 90 min. The method also discriminates single base mismatches. In our perception, it has a wide scope in that it may be applied to the detection of many other GMOs. Graphical abstractAn isothermal and sensitive colorimetric method is described for amplified detection of CaMV 35S promoter sequence in genetically modified organism (GMO). It is based on target DNA-triggered molecular beacon (UMB) termini-binding and exonuclease III assisted target recycling, and on hemin/G-quadruplex (DNAzyme) signal amplification.

中文翻译：

---

基于核酸外切酶 III 辅助靶标回收和氯化血红素/G-四链体 DNA 酶扩增的转基因生物比色检测

摘要描述了一种等温比色法，用于扩增检测转基因生物 (GMO) 中的 CaMV 35S 启动子序列。它基于 (a) 靶标 DNA 触发的未标记分子信标 (UMB) 末端结合，和 (b) 核酸外切酶 III (Exo III) 辅助的靶标回收，以及 (c) 基于氯化血红素/G-四链体 (DNAzyme) 的信号放大. 目标与 G-四链体序列锁定 UMB 的特异性结合触发了 Exo III 的消化。反过来，这会释放活性 G-四链体片段和目标 DNA，用于连续杂交和切割。Exo III 推进循环目标产生大量 G-四链体序列。这些进一步与血红素结合形成 DNAzymes，因此将催化 H2O2 介导的显色酶底物 ABTS2- 氧化，导致绿色产物的形成。这一发现能够以低至 0.23 nM 的浓度对 GMO DNA（分析波长为 420 nm）进行灵敏的比色测定。通过利用等温孵化，这种方法不需要复杂的设备或复杂的合成。分析可在 90 分钟内完成。该方法还区分单碱基错配。在我们看来，它的范围很广，可以应用于许多其他转基因生物的检测。图形摘要描述了一种用于扩增检测转基因生物 (GMO) 中 CaMV 35S 启动子序列的等温且灵敏的比色法。