Abstract：
Analysis of exosomes provides important information for rapid and non-invasive screening of tumors. However, sensitive and convenient detection of exosomes remains technically challenging to date. Herein, a colorimetric aptasensor based on the light-stimulated oxidase-mimicking activity of FITC was constructed for detecting ovarian cancer (OC) exosomes. The aptasensor contained an EpCAM aptamer to capture OC exosomes. Cholesterol and fluorescein (FITC) were used to modify either end of the DNA (DNA anchor). The DNA anchor could combine with exosomes through a hydrophobic reaction between cholesterol and the lipid membrane. FITC oxidized 3,3\',5,5\'-tetramethylbenzidine (TMB) under a 365 nm LED light source in a temporally controllable manner under mild conditions, causing the solution to change from colorless to blue, and the corresponding UV-vis absorbance increased. Based on this principle, the exosomes were qualitatively analyzed by observing the color change with the naked eye. In parallel, the exosome concentration was also detected using UV-vis spectrophotometry. The linear range was from 2 × 105 to 100 × 105 particles per mL with a limit of detection of 1.77 × 105 particles per mL. The developed aptasensor also exhibited favorable selectivity and could discriminate the exosomes from OC cells and normal cells. Besides, the receiver operating characteristic (ROC) curve demonstrates that it is possible to distinguish between patients with OC and healthy donors (HDs) using exosomes as the biomarker. Our technology may expand the applications of DNA-based detection method-enabled OC diagnostic tools.
摘要：
外泌体的分析为肿瘤的快速和非侵入性筛查提供了重要信息。然而,到目前为止，外泌体的灵敏和方便的检测在技术上仍然具有挑战性。在这里，基于FITC的光刺激氧化酶模拟活性，构建了一种比色传感器，用于检测卵巢癌（OC）外泌体。aptasensor包含EpCAM适体以捕获OC外来体。使用胆固醇和荧光素(FITC)修饰DNA的任一端(DNA锚)。DNA锚可以通过胆固醇和脂质膜之间的疏水反应与外泌体结合。FITC氧化3,3\'，5,5'-四甲基联苯胺（TMB）在温和条件下以时间可控的方式在365nmLED光源下，导致溶液从无色变成蓝色，相应的UV-vis吸光度增加。基于这个原则,用肉眼观察外泌体的颜色变化进行定性分析。并行,也使用UV-vis分光光度法检测外泌体浓度。线性范围为2×105至100×105个颗粒/mL，检出限为1.77×105个颗粒/mL。开发的aptasensor还表现出良好的选择性，可以区分OC细胞和正常细胞的外泌体。此外,受试者工作特征(ROC)曲线表明,使用外泌体作为生物标志物,可以区分OC患者和健康供体(HDs).我们的技术可以扩展基于DNA的检测方法启用的OC诊断工具的应用。
