State Key Laboratory for Organic Electronics and Information Displays, Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, Nanjing, 210023, China.
State Key Laboratory for Organic Electronics and Information Displays, Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, Nanjing, 210023, China.
Biosens Bioelectron. 2022 Oct 1;213:114442. doi: 10.1016/j.bios.2022.114442. Epub 2022 May 31.
Identification and detection of extreme rare circulating tumor cells (CTCs) in peripheral blood can precisely monitor cancer recurrence and metastasis, however, how to ultra-sensitively and reliably detect CTCs is a big challenge. In this work, a ratiometric surface-enhanced Raman spectroscopy (SERS)-based strategy for ultra-sensitively and nondestructively detecting CTCs was proposed via CTCs-triggered DNA walker-assisted assembly of plasmonic nanostructure networks consisting of Walker probes and SERS tags. The Walker probes were prepared by modifying FeO@SiO@Au nanoparticles (GMNPs) with ROX-labeled EpCAM aptamer-blocked Zn-specific DNAzyme and hairpin-structured single-stranded DNAs H1, and the SERS tags were constructed by co-labelling hairpin-structured single-stranded DNAs H2 and Raman molecules (DTNB) on Au NPs. The aptamers can recognize EpCAM-positive CTCs via the specific binding to EpCAM, so that the activity of DNAzymes is activated with the assistance of Zn to launch the DNA walker to move around for the cleavage of H1 on GMNPs. The residual fragments of H1 on GMNPs can hybridize with H2 on SERS tags and result in the formation of Walker probe-SERS tag network nanostructures (Nw NSs) with rich SERS hot spots. The reliable SERS detection of CTCs is achieved by the stable ratiometric SERS signals of DTNB and ROX generated from the Nw NSs, and a good linear relation between ratiometric SERS signal and MCF-7 cells concentration was obtained with the detection limit low to 1 cell/mL. The recovery rate of MCF-7 cells in peripheral blood is in the range of 94.0%-104.5%, which indicates a good application prospect of the novel ratiometric SERS cytosensor in the clinic detection of EpCAM-positive CTCs.
鉴定和检测外周血中的极罕见循环肿瘤细胞（CTC）可以精确监测癌症的复发和转移，然而，如何超灵敏和可靠地检测 CTC 是一个巨大的挑战。在这项工作中，通过 CTC 触发的 DNA walker 辅助组装包含 Walker 探针和 SERS 标签的等离子体纳米结构网络，提出了一种基于比率表面增强拉曼光谱（SERS）的超灵敏、非破坏性检测 CTC 的策略。Walker 探针通过用 ROX 标记的 EpCAM 适体封闭的 Zn 特异性 DNA 酶和发夹结构的单链 DNA H1 修饰 FeO@SiO@Au 纳米颗粒（GMNPs）制备，SERS 标签通过在 Au NPs 上共标记发夹结构的单链 DNA H2 和拉曼分子（DTNB）构建。适体可以通过与 EpCAM 的特异性结合识别 EpCAM 阳性 CTC，从而在 Zn 的协助下激活 DNA 酶的活性，启动 DNA walker 移动以切割 GMNPs 上的 H1。GMNPs 上的 H1 的残留片段可以与 SERS 标签上的 H2 杂交，导致具有丰富 SERS 热点的 Walker 探针-SERS 标签网络纳米结构（Nw NSs）的形成。通过来自 Nw NSs 的 DTNB 和 ROX 的稳定比率 SERS 信号实现了对 CTC 的可靠 SERS 检测，并且比率 SERS 信号与 MCF-7 细胞浓度之间获得了良好的线性关系，检测限低至 1 个细胞/mL。外周血中 MCF-7 细胞的回收率在 94.0%-104.5%范围内，表明新型比率 SERS 细胞传感器在临床检测 EpCAM 阳性 CTC 方面具有良好的应用前景。
