(41f) Effect of Surface Roughness On Affinity-Based Cell Capture

Cell-based microfluidic devices have recently attracted interest for a wide range of applications. While affinity based flatbed cell isolation devices have been utilized in many different research fields, research on the effect of nanoscale surface roughness on affinity-based cell isolation efficiency is still lacking. We studied this effect using surfaces modified by a monolayer of close packed silica nano-beads 100 nm-1200 nm in diameter. These surfaces were further bonded to a microfluidic channel and functionalized with anti-CD4 antibodies to capture Jurkat cells (human T lymphocytes) under continuous flow. It is observed that the affinity cell capture first increases with the bead size and then decreases gradually with the bead size. Surprisingly, a dip (a sudden plunge and then recovery) of cell capture efficiency occurs on the decreasing slope, while the location and depth of the dip is dependent on the sample flow rate. Two aspects are considered in an effort to understand why the cell capture efficiency is dependent on surface topography. The first one is from a fluidic dynamic aspect, where simulation of velocity profile inside of a microchannel was performed with and without nanobeads on the channel floor. The second consideration is from a cell mechanical deformation perspective, where capture of glutaraldehyde-fixed Jurkat cells were compared to the capture of live cells. Our study demonstrates that the yield of affinity cell capture can be improved with controlled surface roughness in a microfluidic chip. This study will benefit the future design of more efficient cell isolation devices.