Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715 PR China.
Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing, 400715 PR China.
Biosens Bioelectron. 2017 Jan 15;87:157-163. doi: 10.1016/j.bios.2016.08.032. Epub 2016 Aug 12.
In this work, a sensitive electrochemical biosensing to Pb was proposed based on the high specificity of DNAzymes to Pb. The response signal was efficiently amplified by the catalytic hairpin assembly induced by strand replacement reaction and the formation of dendritic structure DNA (DSDNA) by layer-by-layer assembly. Firstly, in the presence of Pb, the substrate strand (S1) of the Pb-specific DNAzymes was specifically cleaved by Pb. Secondly, one of the two fragments (rS1) introduced into the electrode surface was hybridized with a hairpin DNA (H1) and further replaced by another hairpin DNA (H2) by the hybridization reaction of H1 with H2. The released rS1 then induced the next hybridization with H1. After repeated cycles, the catalytic recycling assembly of H2 with H1 was completed. Thirdly, two bioconjugates of Pt@Pd nanocages (Pt@PdNCs) labeled with DNA S3/S4 and electroactive toluidine blue (Tb) (Tb-S3-Pt@PdNCs and Tb-S4-Pt@PdNCs) were captured onto the resultant electrode surface through the hybridization of S3 and H2, S3 and S4, resulting in the formation of DSDNA triggered by layer-by-layer assembly. This formed DSDNA greatly facilitated the immobilization of manganese(III) meso-tetrakis (4-N-methylpyridiniumyl)-porphyrin (MnTMPyP) as mimicking enzyme. Under the synergistic catalysis of Pt@PdNCs and MnTMPyP to HO reduction, the effective signal amplification of the developed Pb biosensor was achieved. As a result, the sensitive detection of the proposed electrochemical strategy for Pb was greatly improved in the range of 0.1pM-200nM with a detection limit of 0.033pM.
在这项工作中，基于 DNA 酶对 Pb 的高特异性，提出了一种灵敏的电化学生物传感测定方法。通过链置换反应诱导的催化发夹组装和通过层层组装形成树枝状结构 DNA（DSDNA），有效地放大了响应信号。首先，在存在 Pb 的情况下，Pb 特异性 DNA 酶的底物链（S1）被 Pb 特异性切割。其次，两个片段之一（rS1）被引入电极表面与发夹 DNA（H1）杂交，并通过 H1 与 H2 的杂交反应进一步被另一个发夹 DNA（H2）取代。释放的 rS1 然后诱导与 H1 的下一次杂交。经过反复循环，完成了 H2 与 H1 的催化循环组装。第三，两种带有 DNA S3/S4 标记的 Pt@Pd 纳米笼（Pt@PdNCs）生物缀合物（Pt@PdNCs）和电活性甲苯胺蓝（Tb）（Tb-S3-Pt@PdNCs 和 Tb-S4-Pt@PdNCs）通过 S3 和 H2、S3 和 S4 的杂交被捕获到所得电极表面上，导致通过层层组装形成 DSDNA。这种形成的 DSDNA 极大地促进了锰（III）meso-四（4-N-甲基吡啶基）-卟啉（MnTMPyP）作为模拟酶的固定化。在 Pt@PdNCs 和 MnTMPyP 协同催化 HO 还原下，实现了所开发的 Pb 生物传感器的灵敏信号放大。结果，所提出的电化学策略对 Pb 的敏感检测在 0.1pM-200nM 范围内得到了极大的提高，检测限为 0.033pM。
