High-throughput immunomagnetic cell detection using a microaperture chip system

We report a microchip system based on a combination of immunomagnetic separation, microfluidics, and size-based filtration for high-throughput detection of rare cells. In this system, target cells bind to magnetic beads in vitro and flow parallel to a microchip with flow rates of milliliters/minute. A magnetic field draws the bead-bound cells toward the microchip, which contains apertures that allow passage of unbound beads while trapping the target cells. The cells captured on the chip can be investigated clearly under a microscope and released from the chip for further analysis. We first characterize the system by detecting cancer cell lines (MCF-7 and A549) in culture media. We then demonstrate detection of 100 MCF-7 cells spiked in 7.5 mL of human blood to simulate detection of circulating tumor cells present in cancer patient blood samples. On average, 85% of the spiked cells were detected. We expect this system to be highly useful in a wide variety of clinical as well as other applications that seek rare cells.