The Effect of Magnetic Bead Size on the Isolation Efficiency of Lung Cancer Cells in a Serpentine Microchannel with Added Cavities

Abstract

Abstract An investigation was conducted to examine the effect of magnetic bead (MB) size on the effectiveness of isolating lung cancer cells using the immunomagnetic separation (IMS) method in a serpentine microchannel with added cavities (SMAC) structure. Carboxylated-magnetic beads were specifically attached to cells through a modification process using aptamers. Cells immobilized with different sizes (in micrometers) of MBs were captured and isolated in the proposed device for comparison and analysis. A computational model was performed to clarify the working principles of the device. To accurately evaluate the impact of MB sizes on capture efficiency, we have included the issue of MB-cell accumulation at the interface between the vertical inlet and the microfluidic channel, despite it being overlooked in many previous studies. A detailed examination of both the accumulation rate and the capture efficiency was conducted. Our findings demonstrated an increasing trend in binding efficiency as the size of MBs decreased, evidenced by coverage values of 50.5%, 60.1%, and 73.4% for MB sizes of 1.36 μm, 3.00 μm, and 4.50 μm, respectively. Furthermore, the overall capture efficiency (without considering the inlet accumulation) was higher for smaller MBs. However, when accounting for the actual number of cells entering the channel (i.e., the effective capture), larger MBs showed higher capture efficiency. The highest effective capture achieved was 88.4% for the size of 4.50 μm. This research provides a comprehensive insight into the impact of MB size on the performance of IMS-based devices and holds promise for the efficient separation of circulating cancer cells in practical applications.