As one of the DNA damage repair enzymes, uracil-DNA glycosylase (UDG) plays an important role in maintaining genomic integrity. By linked bridge hybridizing-induced split G-quadruplex (SQ), we demonstrate here the construction of a simple and sensitive DNA machine for the detection of UDG activity. The satisfactory split G-quadruplex sequences (SQS) were successfully selected to be the ingredients of SQ formation. In this work, UDG recognized and removed the uracil bases from the stem of hairpin DNA (HP). And then, HP with a low melting temperature hybridized with designed SQS, forming a three-way DNA structure with an SQ. With the addition of Thioflavin T, a dramatical enhancement of fluorescence intensity was presented due to the G-quadruplex/Thioflavin T complex formation. The detection limit was as low as 7.8 × 10⁻³ U/mL. And we also successfully investigated the performance of UDG activity in the HeLa cell lysate. This optical DNA machine with the merits of being simple, rapid, and economical was flexibly suitable for not only active UDG assay but also diverse target detection by adjusting the recognition region of the HP.

作为DNA损伤修复酶之一，尿嘧啶DNA糖基化酶（UDG）在维持基因组完整性方面起着重要作用。通过链接桥杂交诱导的分裂G-四链体（SQ），我们在这里展示了用于检测UDG活性的简单而敏感的DNA机器的构建。成功地选择了令人满意的分裂G-四链体序列（SQS）作为SQ形成的成分。在这项工作中，UDG识别并去除了发夹DNA（HP）茎中的尿嘧啶碱基。然后，低熔点的HP与设计的SQS杂交，形成具有SQ的三向DNA结构。加入硫黄素T后，由于G-四链体/硫黄素T复合物的形成，荧光强度得到了显着提高。检出限低至7.8×10 ^-3 U / mL。并且我们还成功地研究了HeLa细胞裂解物中UDG活性的表现。这种光学DNA机器具有简单，快速和经济的优点，不仅可以灵活地用于主动UDG分析，而且还可以通过调节HP的识别区域来灵活地进行多种靶标检测。