癌症悄无声息地发展到无法手术的晚期阶段。在癌症治疗方案中存在许多限制，但早期诊断可以提高生存率并降低复发率。外泌体是癌细胞释放的生物分子，是临床诊断的有希望的候选物。其中，CD9蛋白是一种重要的外泌体生物标记物，可用于外泌体的检测。因此，在本研究中，首次合成了一个CD9适配体，并应用于一个包含一次性感知膜的扩展门场效应晶体管（EGFET）型生物传感器，以提示在临床环境中检测外泌体的可能性。我们通过系统评估配体的指数富集（SELEX）技术，选择能够特异性靶向CD9蛋白的核酸序列。根据膜电信号的变化来检测外泌体，使用的是一个Au微电极作为扩展门。制备的生物传感器对CD9蛋白具有10.64 pM的检测限度（LOD），在缓冲液中的检测范围为10 pM到1 μM。对于临床试验，人血清样品中外泌体的LOD和检测范围分别为6.41 × 102 exosomes/mL和1 × 103 to 1 × 107 exosomes/mL，结果高度可靠，误差率低。这些发现表明所提出的适配体传感器可以成为一种简单早期诊断外泌体的强大工具。

Cancer progresses silently to the terminal stage of the impossible operable condition. There are many limitations in the treatment options of cancer, but diagnosis in an early stage can improve survival rates and low recurrence. Exosomes are the biomolecules released from cancer cells and are promising candidates for clinical diagnosis. Among them, the cluster of differentiation 9 (CD9) protein is an important exosomal biomarker that can be used for exosome determination. Therefore, here, a CD9 aptamer was first synthesized and applied to an extended-gate field-effect transistor (EGFET)-type biosensor containing a disposable sensing membrane to suggest the possibility of detecting exosomes in a clinical environment. Systematically evaluating ligands using the exponential enrichment (SELEX) technique was performed to select nucleic acid sequences that can specifically target the CD9 protein. Exosomes were detected according to the electrical signal changes on a membrane, which is an extended gate using an Au microelectrode. The fabricated biosensor showed a limit of detection (LOD) of 10.64 pM for CD9 proteins, and the detection range was determined from 10 pM to 1 μM in the buffer. In the case of the clinical test, the LOD and detection ranges of exosomes in human serum samples were 6.41 × 102 exosomes/mL and 1 × 103 to 1 × 107 exosomes/mL, respectively, showing highly reliable results with low error rates. These findings suggest that the proposed aptasensor can be a powerful tool for a simple and early diagnosis of exosomes.