癌症是全球重大的疾病之一，早期階段診斷癌症可以增加患者的存活率，因此有必要建立一個準確的方法來早期診斷癌症。近年來適體被視為有望取代傳統抗體的工具，因此尋找對癌症組織相關的特定標靶具有高專一性和親合力的適體很重要。配體指數增強進化技術(SELEX)是用來篩選對生物相關分子具有高專一性及親和性的適體的一項技術。然而這項技術在大型系統操作上是非常耗時且耗人力，而微流體系統是個可用來改善此技術的強大工具。然而適體的專一性及親和力容易受到酸鹼性、離子種類及濃度的影響，即使可在篩選後再優化，亦顯得複雜且費力。此研究建立一個可以自動化優化適體篩選過程的微流體系統。兩個不同的微流體晶片結合在此系統中，一個晶片用來調整溶液中的離子種類和濃度，而另一個晶片則用來進行配體指數增強進化技術優化。三個適體已被成功篩選出且進行了對卵巢癌組織專一性和親和性的測試，實驗結果顯示在經過優化篩選後的適體(H-45)具有比在先前研究中用未優化的篩選條件篩選出的適體(cTX-36)擁有更好的專一性和親和性。因此，此微流體系統是一個可用來優化適體篩選過程且應用在篩選診斷癌症的人工抗體之利器。

Cancer is one of the most serious diseases globally for decades. Diagnosis of cancer at early stages can significantly increase the survival rate of the patients. Therefore, it is necessary to establish an accurate method for early diagnosis of cancers. Recently, aptamers are considered as promising tools to replace the conventional antibodies. Therefore, screening aptamer candidates with high affinity and specificity towards the specific targets associate with cancer tissues is important. Systematic evolution of ligands by exponential enrichment (SELEX) is one of the most popular processes to screen aptamers with high specificity and affinity toward the biological relevant molecules. However, a bench-top protocol of the SELEX procedure is relatively labor-intensive and time-consuming. Alternatively, microfluidic systems could be a powerful tool to advance SELEX technology. However, specificity and affinity of aptamers are sensitive to several parameters such as pH values, ion species, and ion concentrations, although post-SELEX could be used to optimize aptamers after SELEX process, which could be relatively complicate and laborious. In this study, an integrated microfluidic system was established to carry out optimization of aptamer selection automatically. Two microfluidic chips were integrated in this system, including a formulation chip to formulate ion species and concentrations of binding buffer for the following SELEX process on another optimization-SELEX chip. Three aptamers were screened and tested with their specificity and affinity. Experimental results showed that an aptamer called H-45 which was screened after an optimal condition exhibited higher specificity and affinity toward ovarian cancer tissue samples than another aptamer (i.e. cTX-36) which was screened from the condition without optimization in our previous study. The developed system might be a powerful device for optimization of aptamer selection and could be used for screening of artificial antibodies for cancer diagnosis.

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