Droplet-based immunomagnetic cell separation

Abstract

This paper presents a droplet-based immunomagnetic cell sorter with high cell separation efficiency and a microfluidic cell sorter integrated with a microfluidic mixer and reaction chamber that were provided for the serial cell separation. The conventional matrix-based MACS magnetically activated cell sorter) separates cells with high separation efficiency, however the tiny gaps of the steel bead matrix can damage or trap the cells. The droplet-based MACS (dMACS) system has a high recovery ratio with comparable high separation efficiency due to its non-matrix structure. The slight agitation of cells in droplet, however, cause high false negative ratio. Therefore, we added a buffer container underneath the droplet, which improved the recovery ratio of negative cells. Agitation of the cell suspension was suppressed, which in turn reduced the false positive and negative ratio to less than 3%. The small volume of the droplet of the dMACS limited its application; therefore we integrated the dMACS system with a microfluidic chip that contained a mixer and a reaction chamber to allow continuous separation of the cell suspension. The droplets of negative cells were serially dripped down to a collection reservoir with the addition of buffer. The cell separation efficiency in the microfluidic chip was not as high as dMACS, however the results demonstrated the feasibility of continuous separation in a microfluidic chip.