Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University , Box 332, Shenyang 110819, China.
Anal Chem. 2017 Sep 5;89(17):9292-9298. doi: 10.1021/acs.analchem.7b02073. Epub 2017 Aug 24.
A synthetic DNA machine performs quasi-mechanical movements in response to external intervention, suggesting the promise of constructing sensitive and specific biosensors. Herein, a smart DNA walker biosensor for label-free detection of carcinoembryonic antigen (CEA) is developed for the first time by a novel cascade amplification strategy of exonuclease (Exo) III-assisted target recycling amplification (ERA) and DNA walker. ERA as the first stage of amplification generates the walker DNA, while the autonomous traveling of the walker DNA on the substrate-modified silica microspheres as the second stage of amplification produces an ultrasensitive fluorescent signal with the help of N-methylmesoporphyrin IX (NMM). The DNA machine as a biosensor could be applied for transducing and quantifying signals from isothermal molecular amplifications, avoiding the complicated reporter elements and thermal cycling. The present biosensor achieves a detection limit of 1.2 pg·mL within a linear range of 10 pg·mL to 100 ng·mL for CEA, along with a favorable specificity. The practical applicability of the biosensor is demonstrated by the detection of CEA in human serum with satisfactory results; thus, it shows great potential in clinical diagnosis.
一种合成 DNA 机器可以对外界干预做出准机械运动，这表明构建敏感和特异的生物传感器具有很大的潜力。本文首次通过一种新的级联扩增策略——外切酶（Exo）III 辅助目标循环扩增（ERA）和 DNA walker，开发了一种用于无标记检测癌胚抗原（CEA）的智能 DNA walker 生物传感器。ERA 作为扩增的第一阶段产生 walker DNA，而 walker DNA 在基底修饰的硅微球上的自主运动作为扩增的第二阶段，在 N-甲基甲川卟啉 IX（NMM）的帮助下产生超灵敏的荧光信号。作为生物传感器的 DNA 机器可以用于转换和量化等温分子扩增的信号，从而避免了复杂的报告元件和热循环。该生物传感器在检测 CEA 时，线性范围为 10 pg·mL 至 100 ng·mL，检测限为 1.2 pg·mL，具有良好的特异性。该生物传感器在人血清中检测 CEA 的实际应用表明了其良好的效果，因此在临床诊断中具有很大的应用潜力。
