Micro-slit filter for separation of circulating tumor cells with high recovery and high purity

We present a novel method for separating circulating tumor cells (CTCs) with high recovery and purity at the same time using a micro-slit filter chip and a fully automated fluidic system. Considering white blood cells (WBCs) as big as CTCs are also captured with CTCs during filtration, we amplified the size of CTCs specifically using microbeads (3 μm) coated with anti-Epithelial Cell Adhesion Molecule (anti-EpCAM) to increase the size difference between WBCs and CTCs. The average diameter of MCF-7 cells was increased from 16.5 μm to 23.1 μm. A micro filter chip having an extremely high aspect ratio (AR=3488) rectangular slit was designed to prevent clogging which induces unwanted aggregation, capturing of other small blood cells and consequently decreasing purity. A fully automated fluid control system was implemented for the better reproducibility and the minimization of handling errors. The procedures from blood loading to staining, prior to analysis, were performed automatically. With the optimized condition, separation experiments using 5ml of normal whole blood spiked with 100 MCF-7 cells have demonstrated the reduction of clogging, high recovery (91.1 %) and high purity (52.0 %) at the same time.