腫瘤的轉移是癌症難以治療及高死亡率的重要原因，當腫瘤成長至一定大小後，便會釋放循環腫瘤細胞（Circulating Tumor Cell, CTC）進入循環系統，並藉由循環系統將癌細胞擴散至體內其他器官或組織，相比於傳統診斷出癌症的時間點，許多研究證明可以更早的在血液中發現循環腫瘤細胞的存在，並使癌症的能早期發現、預防與治療，而相較於單顆的CTC，由包含CTC與多種細胞組成的循環腫瘤細胞團簇（CTC cluster）被認為在血液中有更高的存活率及轉移優勢，是癌症研究中的重點趨勢。本研究開發之微流道系統包含兩大功能區域，第一功能區域為利用三段式確定性側向位移技術進行篩選，使CTC團簇與樣本中其他細胞分離，並直接沿著流到晶片的第二功能區域，此區域為細胞抓取暨培養之陷阱陣列，並於結構表面已膠原蛋白修飾，模擬細胞外基質環境，以利於進行癌細胞的貼附及培養。實驗結果顯示，確定性側向位移結構分選大型團簇的效率以及其回收率皆能達95%以上，小型團簇則在漫流速的情況下達80%以上，有鑑於篩選速度與效率的平衡，最終使用5μl/min的樣本體積流速進行全晶片的實驗，並成功的使用陷阱陣列在百顆團簇內達到98.5%的抓取效率，在為期三天的培養中，細胞也能夠穩定貼附與成長，且存活率維持在94.4%以上。

Metastasis is an important reason why cancer is challenging to be treated and has a high mortality. When the tumor grows to a certain size, it will release Circulating Tumor Cell (CTC) into the Circulatory system, and CTCs will spread in the body. Compared with the traditional time point of cancer diagnosis, many studies have proved that the existence of circulating tumor cells could be found in the blood earlier, and cancer can be detected, prevented and treated early. Compared with a single CTC, circulating tumor cell clusters (CTC clusters) composed of CTCs and a variety of cells are considered to have higher viability and metastasis potential in the blood, which is a key point in cancer research. The microfluidic system developed in this research contains two major functional areas. The first functional area is the use of three-level deterministic lateral displacement technology for sorting. CTC clusters are separated from other cells in the sample and flow directly to the second functional area of the chip. This area is a trap array for cell capturing and culturing. The surface has been modified with collagen to build the extracellular matrix environment to promote the attachment and culturing of cancer cells. Experimental results show that the deterministic lateral displacement sorting efficiency and recovery rate of large clusters can reach more than 95%. Both of small clusters can reach more than 80% under the condition of a lower flow rate. In view of the balance of sorting speed and efficiency, a sample volume flow rate of 5μl/min was used to perform a full-chip experiment, and the trap array was successfully used to achieve a capturing efficiency of 98.5% in a hundred clusters. The cells can also attach and grow stably during the three-day culture. And the cell viability remains above 94.4%.

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