Exosomes are nanoscale membrane vesicles actively released by cells and play an important role in the diagnosis of cancer-related diseases. However, it is challenging to efficiently enrich exosomes from extracellular fluids. In this work, we used DNA nanostructures as “nanoweights” during centrifugation to facilitate the enrichment of cancerous exosomes in human serum. Two different DNA tetrahedral nanostructures (DTNs), each carrying a specific aptamer for exosome biomarker recognition, were incubated with clinical samples simultaneously. One DTN triggered the cross-linking of multiple target exosomes and, therefore, enabled low-speed and fast centrifugation for enrichment. The other DTN further narrowed down the target exosome subtype and initiated a hybridization chain reaction (HCR) for sensitive signal amplification. The method enabled the detection of 1.8 × 10² MCF-7-derived exosomes per microliter and 5.6 × 10² HepG2-derived exosomes per microliter, with 1000-fold higher sensitivity than conventional ELISA and 10-fold higher sensitivity than some recently reported fluorescence assays. Besides, the dual-aptamer system simultaneously recognized multiple surface proteins, eliminating the interference risk from free proteins. Thus, this easy-to-operate method can enrich exosomes with excellent specificity and sensitivity and therefore will be appealing in biomedical research and clinical diagnosis.

中文翻译：

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通过 DNA 纳米重量辅助离心对癌症相关外泌体进行快速特异性富集和定量

外泌体是细胞主动释放的纳米级膜囊泡，在癌症相关疾病的诊断中发挥着重要作用。然而，从细胞外液中有效富集外泌体具有挑战性。在这项工作中，我们在离心过程中使用 DNA 纳米结构作为“纳米重量”，以促进人血清中癌性外泌体的富集。将两种不同的 DNA 四面体纳米结构 (DTN) 与临床样本同时孵育，每一种都携带用于外泌体生物标志物识别的特定适体。一个 DTN 触发了多个目标外泌体的交联，因此能够进行低速和快速离心以进行富集。另一个 DTN 进一步缩小了目标外泌体亚型，并启动了杂交链式反应 (HCR) 以进行敏感信号放大。^{每微升2 个}MCF-7 衍生的外泌体和每微升 5.6 × 10 ^{2 个}HepG2 衍生的外泌体，其灵敏度比传统 ELISA 高 1000 倍，比最近报道的一些荧光测定法高 10 倍。此外，双适体系统同时识别多种表面蛋白，消除了游离蛋白的干扰风险。因此，这种易于操作的方法可以以优异的特异性和敏感性富集外泌体，因此在生物医学研究和临床诊断中具有吸引力。