Microslit on a chip: A simplified filter to capture circulating tumor cells enlarged with microbeads

Abstract

Microchips are widely used to separate circulating tumor cells (CTCs) from whole blood by virtues of sophisticated manipulation for microparticles. Here, we present a chip with an 8 μm high and 27.9 mm wide slit to capture cancer cells bound to 3 μm beads. Apart from a higher purity and recovery rate, the slit design allows for simplified fabrication, easy cell imaging, less clogging, lower chamber pressure and, therefore, higher throughput. The beads were conjugated with anti-epithelial cell adhesion molecules (anti-EpCAM) to selectively bind to breast cancer cells (MCF-7) used to spike the whole blood. The diameter of the cell-bead construct was in average 23.1 μm, making them separable from other cells in the blood. As a result, the cancer cells were separated from 5 mL of whole blood with a purity of 52.0% and a recovery rate of 91.1%, and also we confirmed that the device can be applicable to clinical samples of human breast cancer patients. The simple design with microslit, by eliminating any high-aspect ratio features, is expected to reduce possible defects on the chip and, therefore, more suitable for mass production without false separation outputs.

Cellulose Mediated Transferrin Nanocages for Enumeration of Circulating Tumor Cells for Head and Neck Cancer

“…Membrane microfilter-based technique has also been reported to capture CTCs, where ligands are functionalized on the polymer based membrane filter to capture CTCs from blood flowing through the small size pore in the polymer matrix, and show 80% capture efficiency 22 . As the pore sizes of these membranes are very small, micro-filter gets clogged in higher flow rate, causing low capture efficiency [23][24][25] . Density based separation technique have also been used to capture CTCs, where ligands are designed and attached to the surface of microbead to isolate CTC by targeted sedimentation of microbead-CTC complex 26 .…”

Ultrathin silicon nitride membrane with slit-shaped pores for high-performance separation of circulating tumor cells

“…Excessive pressure drop may lead to cell damage or death. 16,44,45 To systematically investigate the dependence of cell viability on the thickness of the filtering membranes, we performed a series of fluid simulations using the software ANSYS Fluent to study the largest pressure drop on the cancer cells with different membrane thicknesses (200 nm, 500 nm, 1 μm, 2 μm, 5 μm, and 10 μm). As the membrane thickness increased, the pressure drops increased (Fig.…”

“…, high capture efficiency, high WBC depletion, and high viability) which can improve the detection sensitivity and be beneficial for subsequent CTC analysis. 13–17 The currently reported CTC separation technologies can be divided into two types: biological affinity-based and physical property-based. 18–21 The former is mainly immunomagnetic-based separation, including positive and negative enrichment methods.…”

“…30,31 Physical properties including size, 32,33 deformability, 34,35 density, 36,37 and electrical properties 38,39 can be also utilized to separate CTCs from blood samples. Among them, the most popular separation method is microfluidic size-based filtration (the typical size of tumor cells: 15–25 μm, the typical size of blood cells: 5–13 μm), 16,32,33,40,41 due to its unlabeled feature, stable capture efficiency, high throughput, and simplicity.…”

“…Several research groups have successfully developed microfluidic devices for CTC capture. 16,32,40,42,43 For example, Yin et al reported a pyramidal microcavity array (8 μm wide rectangular pores) for CTC capture, and the capture efficiency was about 80%. 42 Negishi et al presented a microcavity array (8 μm wide rectangular pores) that can separate CTCs with a capture efficiency of ∼95%.…”