Key Laboratory of Luminescent and Real-Time Analytical Chemistry, Ministry of Education, College of Chemistry and Chemical Engineering , Southwest University , Chongqing 400715 , People's Republic of China.
Anal Chem. 2018 May 15;90(10):6096-6101. doi: 10.1021/acs.analchem.8b00093. Epub 2018 Apr 26.
In this work, a highly sensitive photoelectrochemical (PEC) assay was constructed based on a donor-acceptor (D-A)-type material, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl- alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4- b]thiophene-4,6-diyl} (PTB7-Th), as the photoactive material and polyaniline (PANI) in situ deposited on the surface of PTB7-Th as the signal enhancer. Initially, PTB7-Th, which contains an electron-rich unit as donor and an electron-deficient unit as acceptor with an easy separation of electron-hole pairs and intermolecular electron transfer, provided an excellent photocurrent response. Subsequently, an input target thrombin (TB) was converted to an output single-stranded DNA by a protein converting strategy. The obtained single-stranded DNA thus triggered a rolling circle amplification (RCA) to form a tandem multihairpin DNA nanostructure, which could function as a skeleton for immobilizing manganese porphyrin (MnTMPyP). In the presence of HO and aniline, a PANI layer could be in situ deposited onto the tandem multihairpin DNA nanostructure with use of MnTMPyP as catalyst, leading to a significantly enhanced photocurrent for the detection of TB. The proposed PEC assay presented a wide detection range of 100 fM to 10 nM with a limit of detection (LOD) of 34.6 fM. Furthermore, the proposed strategy provides a PEC analysis method based on PTB7-Th that can significantly improve the photoelectric conversion efficiency and opens an intriguing avenue to establish low background, ultrasensitive, and highly stable analytical techniques.
在这项工作中，构建了基于供体-受体（D-A）型材料聚{4,8-双[5-(2-乙基己基)噻吩-2-基]苯并[1,2-b:4,5-b']二噻吩-2,6-二基--alt-3-氟-2-[(2-乙基己基)-羰基]噻吩[3,4-b]噻吩-4,6-二基}（PTB7-Th）作为光活性材料，以及聚吡咯（PANI）原位沉积在 PTB7-Th 表面作为信号增强剂，构建了一种高灵敏度的光电化学（PEC）分析方法。首先，PTB7-Th 包含一个富电子单元作为供体和一个缺电子单元作为受体，具有电子-空穴对的易于分离和分子间电子转移，提供了出色的光电流响应。随后，通过蛋白质转化策略将输入靶标凝血酶（TB）转化为输出单链 DNA。所得单链 DNA 因此触发滚环扩增（RCA）形成串联多发夹 DNA 纳米结构，可作为固定锰卟啉（MnTMPyP）的骨架。在 HO 和苯胺存在的情况下，可使用 MnTMPyP 作为催化剂，将 PANI 层原位沉积到串联多发夹 DNA 纳米结构上，从而显著增强用于检测 TB 的光电流。所提出的 PEC 分析方法具有 100 fM 至 10 nM 的宽检测范围，检测限（LOD）为 34.6 fM。此外，该策略提供了一种基于 PTB7-Th 的 PEC 分析方法，可以显著提高光电转换效率，并为建立低背景、超灵敏和高稳定的分析技术开辟了一条有趣的途径。
