An optically-induced dielectrophoretic (ODEP) microfluidic platform for isolation of circulating tumor cells (CTCS) after conventional CTC isolation process

Negative selection-based circulating tumor cells (CTCs) isolation method can harvest the CTCs in a label-free manner that is valuable for the subsequent CTC-based assays. However, such cell isolation scheme normally suffers from low CTC purity. To address the issue, the utilization of optically-induced dielectrophoretic (ODEP) force in a microfluidic chip to further purify the CTCs was proposed in this study. The working principle was primarily based on the fact that operating conditions of ODEP for the manipulation of CTCs (prostate cancer 3 as tested cells) and leukocytes were different due to the size difference between these two cells. By fine-tuning the operating conditions of ODEP force, cancer cells can be isolated from blood cells in an effective manner. In this study, operating conditions of ODEP for manipulation the cells were first investigated. The isolation of cancer cells from cell mixtures with different cancer cell purity was carried out. Results revealed that the isolated cancer cells were viable, indicating that such CTC isolation process was relatively cell-friendly. Moreover, the proposed CTC isolation scheme was proved to be able to isolate cancer cells from the cell mixture with high recovery rate (84%-88%), and high purity (82%-89%). As a whole, this study has presented an efficient and effective method for further enhancing the purity of CTCs after the conventional CTC isolation process.