Negative Enrichment of Target Cells by Microfluidic Affinity Chromatography

Abstract

A three-dimensional microfluidic channel was developed for high purity cell separations. This system featured high capture affinity using multiple vertical inlets to an affinity surface. In cell separations, positive selection (capture of the target cell) is usually employed. Negative enrichment, the capture of non-target cells and elution of target cells, has distinct advantages over positive selection. In negative enrichment, target cells are not labeled, and are not subjected to strenuous elution conditions or dilution. As a result, negative enrichment systems are amenable to multi-step processes in microfluidic systems. In previous work, we reported cell capture enhancement effects at vertical inlets to the affinity surface. In this study, we designed a chip that has multiple vertical and horizontal channels, forming a three-dimensional separation system. Enrichment of target cells showed separation purities of 92-96%, compared with straight-channel systems (77% purity). A parallelized chip was also developed for increased sample throughput. A two-channel showed similar separation purity with twice the sample flow rate. This microfluidic system, featuring high separation purity, ease of fabrication and use, is suitable for cell separations when subsequent analysis of target cells is required.

Advances in Microfluidic Materials, Functions, Integration, and Applications

“…The absence of a cell-damaging elution step was advantageous; the method was tested on the separation of lymphocytes and mouse endothelial cells. 324 A better understanding of cell-to-cell variation can be obtained through single-cell analysis. Human glioblastoma cells cultured in a PDMS-glass microfluidic platform were imaged fluorescently to analyze multiple cell proteins simultaneously.…”

Efficient elusion of viable adhesive cells from a microfluidic system by air foam

“…3,18 Using bubble-induced detachment of affinity-adsorbed cells has been reported in recent years. 14,15,19 Surface attached particles may be released by introducing an air-water interface, which creates a net surface tension upon particle. When the net force is larger than the surface adhesive force, the particle-surface linkage may be disrupted, thus releasing the particle.…”

“…While these works demonstrated the potential using air bubbles to release cells from the affinity surface in a straight capillary tube, the adaption to the chip-based microfluidic devices has not been demonstrated 19 due to multiple technical challenges such as air bubble trapping, and irregular flow field of mixture of air bubbles and liquid resulting in low release efficiency. In addition, it was estimated the air-water interface could induce stress on the cell ranging from 20 to 300 dyn/cm 2 according to the position of adhesive cell with respect to the air-water interface.…”

Multiparameter Cell Affinity Chromatography: Separation and Analysis in a Single Microfluidic Channel

“…The cell capture density increased over time, whereas captured cells purity decreased (Figure 4a and 4b). This result is not unexpected, as longer separations can experience more nonspecific binding as the cell surface is increasingly covered with target cells [30-31]. From 5 minutes to 30 minutes, cell density increased from 230±10 to 650±80 cells/mm 2 on the anti-CD19 coated area, and 20±20 to 400±200 cells/mm 2 on the anti-CD4 coated area.…”