Single nucleotide polymorphisms (SNPs) are main causes of differences in human phenotypes and drug resistance, especially the development of genetic diseases. Monitoring SNPs is of significant benefit to drug design and disease diagnosis. In this work, on the basis of tripartite DNAzyme junction formation induced by flap endonuclease 1 (FEN1) invader assay-triggered catalytic hairpin assembly (CHA), we describe an amplified and highly sensitive fluorescent strategy for detecting SNP of K-ras gene with substantial discrimination capability. The mutant DNA (MtDNA) of K-ras gene hybridizes with the sensing probe to inhibit the enzymatic activity of FEN1 to trigger subsequent CHA of three hairpins for the formation of tripartite DNAzyme junctions. And, the fluorescently quenched signal probes are efficiently and cyclically cleaved by the DNAzymes to restore largely magnified fluorescence for detecting MtDNA target sequence at 4.23 fM. Besides, the existence of low levels of MtDNA strands in diluted human serums and high concentrations of wild DNA solutions can be differentiated by such a method, showing its high potential for monitoring various SNPs for biological research and disease diagnosis.

单核苷酸多态性（SNPs）是导致人类表型和耐药性差异的主要原因，尤其是遗传疾病的发展。监测 SNP 对药物设计和疾病诊断具有重要意义。在这项工作中，基于由瓣内切酶 1 (FEN1) 入侵者检测触发的催化发夹组装 (CHA) 诱导的三方 DNAzyme 连接形成，我们描述了一种用于检测 K-ras 基因 SNP 的扩增和高灵敏度荧光策略，具有大量辨别能力。K-ras基因的突变DNA（MtDNA）与传感探针杂交，抑制FEN1的酶活性，触发三个发夹的后续CHA，形成三联脱氧核糖核酸酶连接。和，荧光猝灭的信号探针被 DNAzymes 有效和循环切割，以恢复大大放大的荧光，用于检测 4.23 fM 的 MtDNA 靶序列。此外，通过这种方法可以区分稀释的人血清中存在低水平的 MtDNA 链和高浓度的野生 DNA 溶液，显示其在监测各种 SNP 用于生物学研究和疾病诊断方面的巨大潜力。