School of Environmental and Biological Engineering , Nanjing University of Science and Technology , Nanjing 210094 , People's Republic of China.
Center for Advanced Analytical Science, School of Chemistry and Chemical Engineering, School of Civil Engineering , Guangzhou University , Guangzhou 510006 , People's Republic of China.
ACS Sens. 2019 Jan 25;4(1):235-241. doi: 10.1021/acssensors.8b01357. Epub 2019 Jan 8.
Sensitive and selective sensing of biological molecules is fundamental to disease diagnosis and infectious disease surveillance. Herein, an ultrasensitive and highly selective electrochemical DNA biosensor is described by exploiting the electrochemically controlled reversible addition-fragmentation chain-transfer (eRAFT) polymerization as a signal amplification strategy and the peptide nucleic acid (PNA) probes as the recognition elements. Specifically, the PNA probes with a thiol at their 5'-terminals are anchored to a gold electrode surface (via gold-sulfur self-assembly) for sequence-specific recognition of target DNA (tDNA) fragments, of which the phosphate sites serve as the anchorages for the targeted labeling (via the well-established phosphate-Zr-carboxylate chemistry) of the carboxyl-group-containing chain-transfer agents (CTAs) for the succedent eRAFT polymerization, wherein the initiating radicals are generated through electrochemical reduction of aryl diazonium salts under a potentiostatic condition. In the presence of ferrocenylmethyl methacrylate (FcCH═CH) as the monomer, the grafting of polymer chains from the CTA-anchored sites as a result of the eRAFT polymerization brings numerous electroactive Fc tags to the electrode surface, outputting a high electrochemical sensing signal even in the presence of trace amounts of tDNA fragments. Under the optimized conditions, the linear range of the described electrochemical DNA biosensor spans from 10 aM to 10 pM ( R = 0.998), with an attomolar detection limit (4.1 aM) being achieved. Moreover, the described electrochemical DNA biosensor is highly selective and applicable to the sensing of tDNA fragments in complex serum samples. Given its high efficiency, easy operation, and low cost, this biosensor shows great promise in real applications.
对生物分子的敏感和选择性检测对于疾病诊断和传染病监测至关重要。在此，通过利用电化学控制的可逆加成-断裂链转移（eRAFT）聚合作为信号放大策略，并采用肽核酸（PNA）探针作为识别元件，描述了一种超灵敏和高度选择性的电化学 DNA 生物传感器。具体而言，具有巯基在其 5'末端的 PNA 探针通过金-硫自组装锚定到金电极表面，用于特异性识别目标 DNA（tDNA）片段，其中磷酸位点作为锚定点，用于靶向标记（通过成熟的磷酸-Zr-羧酸化学）含羧基的链转移剂（CTA），随后进行 eRAFT 聚合，其中引发自由基通过在恒电位条件下电化学还原芳基重氮盐生成。在存在二茂铁基甲基丙烯酸甲酯（FcCH=CH）作为单体的情况下，由于 eRAFT 聚合，CTA 锚定位点的聚合物链接枝将大量电化学活性的 Fc 标签带到电极表面，即使存在痕量的 tDNA 片段，也能输出高电化学传感信号。在优化条件下，所描述的电化学 DNA 生物传感器的线性范围从 10 aM 到 10 pM（R=0.998），检测限低至 4.1 aM（4.1 aM）。此外，所描述的电化学 DNA 生物传感器具有高度选择性，适用于复杂血清样品中 tDNA 片段的检测。鉴于其高效率、易于操作和低成本，该生物传感器在实际应用中具有很大的应用前景。
