We herein describe a novel washing-free electrochemical strategy for target DNA detection by utilizing the peroxidase mimicking DNAzyme. The DNAzymeincorporated DNA probes, the key components of this strategy, are designed to be not able to form G-quadruplex structure in the initial state such that the peroxidase mimicking activity of DNAzyme is kept suppressed. The DNAzyme sequences, however, would be converted to the catalytically active G-quadruplex structure by the presence of target DNA, whose peroxidase mimicking activity then promote the precipitation reaction of 4-chloronaphthol (4-CN) on the electrode. Due to the precipitates produced on the electrode surface, the electrochemical reaction between the redox materials and electrode surface is inhibited, consequently leading to a significant increase of the impedance signal. Based on this novel electrochemical design principle, we successfully detected the target DNA from sexually transmitted disease (STD) pathogens such as Chlamydia trachomatis, Trichomonas vaginalis, and Herpes simplex virus type 2 in real patient samples, verifying its practical diagnostic capability in the clinical applications.

我们在此描述了一种新型的免洗电化学策略，用于通过利用过氧化物酶模拟DNA酶来检测目标DNA。掺入DNAzyme的DNA探针是该策略的关键组成部分，被设计为不能在初始状态下形成G-四链体结构，从而使DNAzyme的过氧化物酶模拟活性得以抑制。然而，通过靶DNA的存在，DNA酶序列将被转化为具有催化活性的G-四链体结构，其过氧化物酶模拟活性随后促进了4-氯萘酚（4-CN）在电极上的沉淀反应。由于在电极表面上产生沉淀物，氧化还原材料和电极表面之间的电化学反应受到抑制，因此导致阻抗信号显着增加。真实患者样本中的沙眼衣原体，阴道毛滴虫和单纯疱疹病毒2型，证实了其在临床应用中的实用诊断能力。