DNA damage repair is one of the foremost factors leading to changes in tumor drug resistance. The analysis of Flap endonuclease 1 (FEN1), a kind of pivotal enzyme in various DNA metabolic pathways, has been of great support to tumor research and the development of chemotherapeutics. Nevertheless, few analytical techniques can achieve quantitative and simplified FEN1 measurement. Here, we constructed a double-wing switch nanodevice (DWSN)-mediated primer exchange technique for rapid and label-free quantification of FEN1 activity. Target FEN1 triggered the generation of numerous telomeric repeat fragments in different lengths through recognizing the three-base mismatched sites on the DWSN to release the 5′ Flaps. Further binding to the fluorescent dye ThT resulted in significantly enhanced fluorescence. This study broke the limitation of traditional single-site identification and demonstrated good sensitivity and specificity with detection limits up to 0.55 mU. Besides, the extraordinary analytical performance allowed the method to be utilized to monitor FEN1 extracted from cells and clinical serum samples and to compare the effect of targeted FEN1 inhibitors.

DNA损伤修复是导致肿瘤耐药性改变的最重要因素之一。Flap 核酸内切酶 1 (FEN1) 是多种 DNA 代谢途径中的一种关键酶，其分析对肿瘤研究和化学疗法的发展提供了重要支持。然而，很少有分析技术可以实现定量和简化的 FEN1 测量。在这里，我们构建了一种双翼开关纳米器件 (DWSN) 介导的引物交换技术，用于快速和无标记地量化 FEN1 活性。目标 FEN1 通过识别 DWSN 上的三碱基错配位点以释放 5' Flaps，触发产生大量不同长度的端粒重复片段。进一步结合荧光染料 ThT 导致荧光显着增强。本研究打破了传统单点鉴定的局限性，具有良好的灵敏度和特异性，检出限高达0.55 mU。此外，非凡的分析性能使该方法可用于监测从细胞和临床血清样本中提取的 FEN1，并比较靶向 FEN1 抑制剂的效果。