Cholinesterases (ChEs) are important indicators of neurological disease, hepatocellular carcinoma, and organophosphate poisoning. In this work, a MnO₂ switch-bridged DNA walker was developed for ultrasensitive sensing of ChEs activity. The fuel strands loaded MnO₂ switch was designed to bridge the hydrolysis activity of ChEs and the running of the DNA walker. Under the action of ChE, the substrate butyrylcholine is first catalytically hydrolyzed to thiocholine, which then mediates MnO₂ nanosheet reduction to Mn²⁺, releasing the fuel strands into solution. The fuel strands as substitute targets then trigger the continuous operation of DNA walker with the aid of Mn²⁺, generating detectable fluorescence responses. The detection of ChE activity is converted to DNA detection in this method. Benefited from the robust operation and amplification effect of DNA walker, a wide linear range between the BChE activity and fluorescence intensity of nearly six orders of magnitude (1000–0.005 U/mL) and a limit of detection as low as 0.0008 U/mL are achieved. This allows the direct determination of BChE activity in clinical serum samples without any pretreatments. Moreover, the proposed method has remarkable capabilities for inhibitor (organophosphorus pesticide) screening and quantification, and organophosphorus pesticide detection in real samples is also achieved. Therefore, the MnO₂ switch-bridged DNA walker represents a powerful tool for ultrasensitive sensing of ChEs and organophosphorus pesticides, and has great application potential in clinical diagnosis, therapeutics, and drug screening.

胆碱酯酶（ChEs）是神经系统疾病，肝细胞癌和有机磷中毒的重要指标。在这项工作中，开发了MnO ₂开关桥式DNA Walker，用于ChEs活性的超灵敏检测。负载燃料线的MnO ₂开关旨在桥接ChEs的水解活性和DNA Walker的运行。在ChE的作用下，底物丁酰胆碱首先被催化水解为硫代胆碱，然后将MnO ₂纳米片还原成Mn ²⁺，从而将燃料链释放到溶液中。燃料束作为替代目标，然后借助Mn ²⁺触发DNA Walker的连续运行，产生可检测的荧光响应。通过这种方法，将ChE活性的检测转换为DNA检测。得益于DNA Walker强大的操作和扩增作用，BChE活性与荧光强度之间的线性范围接近六个数量级（1000-0.005 U / mL），检测限低至0.0008 U / mL。实现。这可以直接测定临床血清样品中的BChE活性，而无需任何预处理。而且，该方法具有显着的抑制剂（有机磷农药）的筛选和定量能力，还实现了实际样品中有机磷农药的检测。因此，MnO ₂ 开关桥式DNA Walker代表了ChEs和有机磷农药超灵敏检测的强大工具，在临床诊断，治疗和药物筛选中具有巨大的应用潜力。