State Key Laboratory for Organic Electronics and Information Displays, Jiangsu Key Laboratory of Smart Biomaterials and Theragnostic Technology, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023, China.
Anal Chem. 2024 Nov 26;96(47):18681-18689. doi: 10.1021/acs.analchem.4c03063. Epub 2024 Nov 17.
Cancer-derived exosomes carry a large number of specific molecular profiles from cancer cells and have emerged as ideal biomarkers for early cancer diagnosis. Accurate detection of ultralow-abundance exosomes in complex biological samples remains a great challenge. Herein, a novel SERS aptasensor powered by cascaded signal amplification of CRISPR/Cas13a -cleavage and catalytic hairpin assembly (CHA) was proposed for ultrasensitive detection of gastric cancer-derived exosomes, which included hairpin-structured recognition aptamers (MUC1-apt), cascaded signal amplification (i.e., CRISPR/Cas13a -cleavage and CHA), SERS tags, and silver nanorods (AgNRs) sensing chip. In the presence of SGC-7901 cell-derived exosomes, MUC1-apt specifically bound to MUC1 proteins highly expressed on exosomes its contained MUC1 aptamer with its exposed RNA fragments activating the CRISPR/Cas13a -cleavage to cleave the uracil-modified hairpin reporter, and the cleavage products further triggered the downstream CHA reaction to form numerous duplexes, which can, in turn, capture a large number of SERS tags onto the AgNRs sensing chip to generate a significantly enhanced Raman signal. The proposed SERS aptasensor exhibits good performance on analysis of exosomes, i.e., rapid response within 60 min, single-particle sensitive detection from a 2 μL biological sample, good specificity in distinguishing SGC-7901 cell-derived exosomes against other exosomes, good uniformity, excellent repeatability, and satisfactory recoveries in human serum, and good universality to expand the detection of multiplex exosomes, which indicates that the SERS aptasensor provides a valuable reference for clinical diagnosis of early cancer.
癌症来源的外泌体携带大量来自癌细胞的特定分子特征，已成为早期癌症诊断的理想生物标志物。在复杂的生物样本中准确检测超低丰度的外泌体仍然是一个巨大的挑战。在此，提出了一种基于 CRISPR/Cas13a 切割和催化发夹组装（CHA）级联信号放大的新型 SERS 适体传感器，用于超灵敏检测胃癌来源的外泌体，其包括发夹结构识别适体（MUC1-apt）、级联信号放大（即 CRISPR/Cas13a 切割和 CHA）、SERS 标签和银纳米棒（AgNRs）传感芯片。在 SGC-7901 细胞来源的外泌体存在下，MUC1-apt 特异性结合到外泌体上高度表达的 MUC1 蛋白，其包含的 MUC1 适体与其暴露的 RNA 片段激活 CRISPR/Cas13a 切割，切割产物进一步触发下游 CHA 反应，形成大量双链体，从而将大量 SERS 标签捕获到 AgNRs 传感芯片上，产生显著增强的拉曼信号。所提出的 SERS 适体传感器在外泌体分析方面表现出良好的性能，即 60 分钟内快速响应，从 2 μL 生物样本中单颗粒敏感检测，能够区分 SGC-7901 细胞来源的外泌体和其他外泌体，具有良好的特异性，在人血清中具有良好的均匀性、出色的重复性和令人满意的回收率，以及良好的通用性，可扩展对多种外泌体的检测，这表明 SERS 适体传感器为癌症早期的临床诊断提供了有价值的参考。
