State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080, China.
Biosens Bioelectron. 2014 Sep 15;59:58-63. doi: 10.1016/j.bios.2014.03.012. Epub 2014 Mar 15.
This work demonstrates an aptasensor for ultrasensitive electrochemiluminescence (ECL) detection of thrombin based on an "off-on-off" approach. The system is composed of an Eu(3+)-doped CdS nanocrystals (CdS:Eu NCs) film on glassy carbon electrode (GCE) as ECL emitter. Then gold nanoparticles (AuNPs) labeled hairpin-DNA probe (ssDNA1) containing thrombin-binding aptamer (TBA) sequence was linked on the NCs film, which led to ECL quenching (off) as a result of Förster-resonance energy transfer (FRET) between the CdS:Eu NC film and the proximal AuNPs. Upon the occurrence of hybridization with its complementary DNA (ssDNA2), an ECL enhancement (on) occurred owing to the interactions of the excited CdS:Eu NCs with ECL-induced surface plasmon resonance (SPR) in AuNPs at large separation. Thrombin could induce ssDNA1 forming a G-quadruplex and cause the AuNPs to be close to CdS:Eu NCs film again, which resulted in an enhanced ECL quenching (off). This "off-on-off" system showed a maximum 7.4-fold change of ECL intensity due to the configuration transformation of ssDNA1 and provides great sensitivity for detection of thrombin in a wide detection range from 50 aM to 1 pM.
本工作展示了一种基于“关-开-关”策略的适体传感器，用于超灵敏电致化学发光（ECL）检测凝血酶。该系统由玻璃碳电极（GCE）上的 Eu(3+)-掺杂 CdS 纳米晶体（CdS:Eu NCs）薄膜作为 ECL 发射器组成。然后，将含有凝血酶结合适体（TBA）序列的金纳米粒子（AuNPs）标记的发夹 DNA 探针（ssDNA1）连接到 NCs 薄膜上，由于 CdS:Eu NC 薄膜和近邻 AuNPs 之间的Förster 共振能量转移（FRET），导致 ECL 猝灭（关）。当与互补 DNA（ssDNA2）发生杂交时，由于激发的 CdS:Eu NCs 与 AuNPs 中的 ECL 诱导表面等离子体共振（SPR）之间的相互作用，会发生 ECL 增强（开）。由于 ssDNA1 形成 G-四链体，导致 AuNPs 再次接近 CdS:Eu NCs 薄膜，从而导致 ECL 猝灭（关）增强。由于 ssDNA1 的构象转换，该“关-开-关”系统显示出最大 7.4 倍的 ECL 强度变化，为凝血酶在 50 aM 至 1 pM 的宽检测范围内的检测提供了高灵敏度。
