Abstract：
Exosomes are closely associated with tumor development and are regarded as viable biomarkers for cancer. Here, a ratiometric fluorescence method was proposed for the one-step and label-free detection of plasma exosomes. A bicolor streptavidin magnetic beads were specifically created with an immobilized Cy5-labeled hairpin aptamer for CD63 (Cy5-Apt) on its surface to identify exosome, and a green color SYBR Green I (SGI) embedded in the stem of Cy5-Apt to respond to exosomes. After exosome capture, the Cy5-Apt could undergo a conformational shift and release the encapsulated SGI, allowing exosome measurement based on the fluorescence ratio of Cy5 and SGI. The enrichment, separation and detection of exosomes in proposed method could be completed in one step (30 min), which is a significant improvement over previous method. Furthermore, the use of ratiometric fluorescence and magnetic separation allows for exosome enrichment and interference elimination from complex matrices, improving accuracy and sensitivity. Particularly, the assay could detect exosomes in plasma and has potential to distinguish lung cancer patients from healthy volunteers with an area under the receiver operator characteristic curve of 0.85. Besides, the study provided an efficient method for analyzing the various divisions of exosomes by merely modifying the aptamer, which holds great promise for point-of-care applications.
摘要：
外泌体与肿瘤的发展密切相关，被认为是癌症的生物标志物。这里,提出了一种比率荧光法用于血浆外泌体的一步无标记检测。双色链霉亲和素磁珠在其表面上用固定的Cy5标记的CD63发夹适体（Cy5-Apt）专门创建，以识别外泌体，和绿色SYBR绿色I（SGI）嵌入在Cy5-Apt的茎响应外泌体。外泌体捕获后，Cy5-Apt可以经历构象移位并释放封装的SGI，允许基于Cy5和SGI的荧光比率进行外泌体测量。浓缩，所提出的方法中外泌体的分离和检测可以在一个步骤(30分钟)中完成，这是对以前方法的重大改进。此外，使用比率荧光和磁分离允许外泌体富集和干扰消除复杂的基质，提高精度和灵敏度。特别是,该试验可以检测血浆中的外来体,并有可能区分肺癌患者和健康志愿者,受试者操作特征曲线下面积为0.85.此外,该研究提供了一种仅通过修饰适体来分析外泌体的各种分裂的有效方法，这对即时护理应用有着巨大的希望。
