DNA methyltransferase catalyzes the methylation process of DNA. As a potential biomarker, methyltransferase activity assay has attracted more and more attention. Herein, we present a new biosensor based on cascade invasive reactions for DNA methyltransferase activity analysis. The sensing probes on the biosensor were first methylated by the Dam MTase and then cleaved by the DpnI endonuclease. The cleaved probe acted as upstream probe for the invasion reaction, triggering a highly sensitive signal amplification reaction that produced a strong fluorescent signal. After detection, the cleaved probes were extended by DNA polymerase, and regenerated to be an intact sensor. Meanwhile, as the invasion reaction was a sequence-independent signal amplification method, our proposed biosensor could be a universal strategy for other enzyme activity analysis, simply by replacing the recognition sequence.

DNA甲基转移酶催化DNA的甲基化过程。作为潜在的生物标志物，甲基转移酶活性测定法引起了越来越多的关注。在这里，我们提出了一种基于级联入侵反应的新型生物传感器，用于DNA甲基转移酶活性分析。生物传感器上的传感探针首先被Dam MTase甲基化，然后被DpnI核酸内切酶切割。裂解的探针充当入侵反应的上游探针，触发高度敏感的信号放大反应，产生强烈的荧光信号。检测后，切割的探针通过DNA聚合酶延伸，并再生为完整的传感器。同时，由于入侵反应是一种不依赖序列的信号放大方法，因此我们提出的生物传感器可能是其他酶活性分析的通用策略，