Abstract：
Here, a separation-free and label-free portable aptasensor is developed for rapid and sensitive analysis of tumor-derived exosomes (TEXs). It integrated a parallel rolling circle amplification (RCA) reaction, selective binding of metal ions or small molecules to nucleic acid-specific conformations, and a low-cost, highly sensitive handheld fluorometer. Lung cancer, for example, is targeted with two typical biomarkers (mucin 1 and programmed cell death ligand 1 (PD-L1)) on its exosomes. The affinity of aptamers to the targets modulated the amount of RCA products (T-Hg2+-T and cytosine (C)-rich single-stranded DNA), which in turn affected the fluorescence intensity of quantum dots (QDs) and methylene blue (MB). The results revealed that the limit of detection (LOD) of the handheld fluorometer for cell-derived exosomes can be as low as 30 particles mL-1. Moreover, its specificity, sensitivity, and area under the curve (AUC) are 93% (14/15), 92% (23/25), and 0.956, as determined by the analysis of 40 clinical samples. Retesting 16 of these samples with the handheld fluorometer yielded strong concordance between the fluorometer results and those acquired from clinical computed tomography (CT) and pathology.
摘要：
这里,开发了一种无分离，无标签的便携式aptasensor，用于快速，灵敏地分析肿瘤衍生的外来体（TEX）。它集成了平行滚环扩增（RCA）反应，金属离子或小分子与核酸特异性构象的选择性结合，和一个低成本的，高灵敏度手持式荧光计。肺癌,例如,在其外泌体上靶向两种典型的生物标志物(粘蛋白1和程序性细胞死亡配体1(PD-L1))。适体对靶标的亲和力调节了RCA产物（T-Hg2+-T和富含胞嘧啶（C）的单链DNA）的量，进而影响量子点(QDs)和亚甲基蓝(MB)的荧光强度。结果表明，手持式荧光计用于细胞衍生的外来体的检测限（LOD）可低至30颗粒mL-1。此外，它的特异性，灵敏度,曲线下面积（AUC）为93%（14/15），92%（23/25），和0.956,如通过对40个临床样品的分析所确定的。用手持式荧光计重新测试这些样品中的16个，在荧光计结果与从临床计算机断层扫描（CT）和病理学获得的结果之间产生了强烈的一致性。
