Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Anal Chem. 2022 Mar 1;94(8):3685-3692. doi: 10.1021/acs.analchem.1c05436. Epub 2022 Feb 14.
Covalent organic frameworks (COFs) have attracted widespread attention in the electrochemiluminescence (ECL) field owing to their high load capacity of ECL luminophores and porous structures, but their ECL performance is still limited by the intrinsic poor conductivity (generally <10 S m). To address this shortcoming, we used 2,3,6,7,10,11-hexaaminotriphenylene (HATP) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) to synthesize a conductive COF (HHTP-HATP-COF, conductivity = 3.11 × 10 S m). Compared with HATP, HHTP, and low-conductive HHTP-DABZ-COF, HHTP-HATP-COF exhibited superior ECL performance, not only because HHTP-HATP-COF possessed massive ECL luminophores but also because its conductive porous framework accelerated charge transport in the whole framework and improved the utilization ratio of ECL luminophores. More interestingly, the ECL intensity of the HHTP-HATP-COF/SO system was further improved after pre-reduction electrolysis due to the accumulation of HHTP-HATP-COF cation radicals. The experimental results showed that the ECL intensity of the HHTP-HATP-COF/SO system after pre-reduction was about 1.64-, 3.96-, 6.88-, and 8.09-fold higher than those of HHTP-HATP-COF/SO, HHTP-DABZ-COF/SO, HHTP/SO, and HATP/SO systems, respectively. Considering the superior ECL property of the HHTP-HATP-COF/SO system after pre-reduction, it was used as a high-efficient ECL beacon together with an aptamer/protein proximity binding-induced three-dimensional bipedal DNA walker to construct an ultrasensitive biosensor for thrombin detection, which displayed broad linearity (100 aM to 1 nM) with a detection limit of 62.1 aM. Overall, the work offered effective ways to increase ECL performance by the enhancement of conductivity and by the pre-reduction, proposing new ideas to design high-efficiency COF-based ECL materials and endowing conductive COFs with ECL biosensor application for the first time.
共价有机骨架（COFs）由于其高负载能力的电致化学发光（ECL）发光体和多孔结构，在 ECL 领域引起了广泛关注，但它们的 ECL 性能仍然受到固有低导电性（通常 <10 S m）的限制。为了解决这一缺点，我们使用 2,3,6,7,10,11-六氨基三苯（HATP）和 2,3,6,7,10,11-六氢三苯（HHTP）合成了一种导电 COF（HHTP-HATP-COF，电导率=3.11×10 S m）。与 HATP、HHTP 和低导电 HHTP-DABZ-COF 相比，HHTP-HATP-COF 表现出优异的 ECL 性能，这不仅是因为 HHTP-HATP-COF 具有大量的 ECL 发光体，还因为其导电多孔骨架加速了整个骨架中的电荷传输，并提高了 ECL 发光体的利用率。更有趣的是，由于 HHTP-HATP-COF 阳离子自由基的积累，HHTP-HATP-COF/SO 体系在预还原电解后，其 ECL 强度进一步提高。实验结果表明，HHTP-HATP-COF/SO 体系预还原后的 ECL 强度分别比 HHTP-HATP-COF/SO、HHTP-DABZ-COF/SO、HHTP/SO 和 HATP/SO 体系高 1.64、3.96、6.88 和 8.09 倍。考虑到预还原后 HHTP-HATP-COF/SO 体系优越的 ECL 性能，它被用作高效的 ECL 信标，与适配体/蛋白质接近结合诱导的三维双足 DNA walker 一起构建了用于凝血酶检测的超灵敏生物传感器，其线性范围很宽（100 aM 至 1 nM），检测限低至 62.1 aM。总的来说，该工作通过增强导电性和预还原提供了提高 ECL 性能的有效方法，为设计高效 COF 基 ECL 材料提供了新的思路，并首次赋予导电 COFs 在 ECL 生物传感器中的应用。
