School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China.
Biosens Bioelectron. 2018 Mar 15;101:1-6. doi: 10.1016/j.bios.2017.09.045. Epub 2017 Sep 28.
The ability to directly detect double-stranded DNA (dsDNA) without sequence-preference continues to be a major challenge. Herein, we report an electrochemical method for the direct, highly sensitive detection of dsDNA based on the strand replacement of dsDNA by peptide nucleic acid (PNA) and the in situ growth of electroactive polymers through the surface-initiated electrochemically mediated atom transfer radical polymerization (SI-eATRP). Thiolated PNA molecules are firstly self-assembled onto gold electrode surface for the specific recognition of target dsDNA (dsDNA-T), which in turn leads to the formation of a high density of PNA/DNA heteroduplexes on the electrode surface for the subsequent attachment of ATRP initiators via the phosphate-Zr-carboxylate chemistry. By applying a negative potential to the electrode, the air-stable Cu deactivators can be reduced into the Cu activators so as to trigger the surface-initiated polymerization for the in situ growth of electroactive polymers. Due to the strand replacement of dsDNA by PNA, dsDNA can be directly detected without sequence-preference. Besides, the growth of polymers enables the modification of numerous electroactive probes, thereby greatly improving the electrochemical signal. Under optimal conditions, a good linearity between the electrochemical signal and the logarithm of dsDNA-T concentration over the range from 1.0 fM to 1.0nM, with a detection limit of 0.47 fM, can be obtained. Results indicate that it is highly selective, and holds high anti-interference capability in the presence of human serum samples. Therefore, this method offers great promises in providing a universal and efficient solution for the direct detection of dsDNA.
直接检测双链 DNA（dsDNA）而无需序列偏好仍然是一个主要挑战。在此，我们报告了一种基于肽核酸（PNA）的 dsDNA 链置换和通过表面引发电化学介导原子转移自由基聚合（SI-eATRP）原位生长电活性聚合物的电化学方法，用于直接、高灵敏度检测 dsDNA。巯基化 PNA 分子首先自组装到金电极表面，用于特异性识别靶 dsDNA（dsDNA-T），这反过来又导致在电极表面形成高密度的 PNA/DNA 异源双链体，用于随后通过磷酸盐-Zr-羧酸酯化学连接 ATRP 引发剂。通过向电极施加负电势，可以将稳定的空气 Cu 失活剂还原成 Cu 活化剂，从而触发表面引发聚合以原位生长电活性聚合物。由于 PNA 对 dsDNA 的链置换，dsDNA 可以直接检测，而无需序列偏好。此外，聚合物的生长允许修饰大量电活性探针，从而大大提高电化学信号。在最佳条件下，可以在 1.0 fM 至 1.0 nM 的范围内获得电化学信号与 dsDNA-T 浓度对数之间的良好线性关系，检测限为 0.47 fM。结果表明，该方法具有高度选择性，并且在存在人血清样品时具有高抗干扰能力。因此，该方法为直接检测 dsDNA 提供了一种通用且有效的解决方案。
