Antibody-Functionalized Fluid-Permeable Surfaces for Rolling Cell Capture at High Flow Rates  Sukant Mittal, Ian Y. Wong, William M. Deen, Mehmet Toner  Biophysical Journal  Volume 102, Issue 4, Pages 721-730 (February 2012) DOI: 10.1016/j.bpj.2011.12.044 Copyright © 2012 Biophysical Society Terms and Conditions

Figure 1 (A) Enhanced cell transport to a fluid-permeable capture surface is achieved by diverting streamlines. (B) Gentle cell rolling and arrest on the capture surface occur due to reduced shear and increased cell-surface interactions. (C) Scanning electron micrograph of polycarbonate surface with 200 nm pores and 10% porosity; schematic of microfluidic device assembly and dimensions. (D) Fluid flow rates through the top and bottom outlets vary linearly with increasing pressure; their ratio is constant and precisely controlled with the use of high-resistance outlets. Each marker is the average of five experiments per condition. Biophysical Journal 2012 102, 721-730DOI: (10.1016/j.bpj.2011.12.044) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 2 Theoretical particle trajectories (dashed black lines) and fluid velocity field vectors (color) in channels with (A) solid surface (A = 0%) and (B) fluid-permeable surface (A = 70%). The color bar corresponds to the magnitude of fluid velocity vectors. Experimentally measured particle velocities tracked in channels with (C) solid surface (A = 0%) and (D) fluid-permeable surface (A = 70%). Biophysical Journal 2012 102, 721-730DOI: (10.1016/j.bpj.2011.12.044) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 3 Experimental measurements of cell surface velocity (markers) as a function of percentage permeation flux A and channel distance. Porous surface was not functionalized. Solid lines are best-fit linear regressions. Each marker and error bar is the average and standard deviation of 30 cells per condition. Biophysical Journal 2012 102, 721-730DOI: (10.1016/j.bpj.2011.12.044) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 4 Instantaneous velocity and displacement trajectories for PC3 cancer cells transported to (A and B) noncomplementary anti-IgG, exhibiting rolling motion at constant speed, and (C and D) anti-EpCAM fluid-permeable surfaces at x = 3 cm with A = 70%, exhibiting rolling before complete arrest. Biophysical Journal 2012 102, 721-730DOI: (10.1016/j.bpj.2011.12.044) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 5 (A) Capture efficiency of PC3 cancer cells at increasing flow rates on complementary anti-EpCAM porous surfaces (red squares), anti-EpCAM solid surfaces (red triangles), noncomplementary anti-IgG porous surfaces (green circles), and anti-IgG solid surfaces (green triangles). Each marker and error bar is the average and SD of three experiments. (B) Capture profile varies along the channel length on an anti-EpCAM porous capture surface at Qin= 6 mL/h and A = 70%. The transverse wall velocity vw0 = 141 μm/s. (C–F) Representative fluorescence micrograph of captured PC3 cells at x = 3 cm for (C) anti-EpCAM porous surface, (D) anti-IgG porous surface, (E) anti-EpCAM solid surface, and (F) anti-IgG solid surface. Scale bar is 100 μm. Biophysical Journal 2012 102, 721-730DOI: (10.1016/j.bpj.2011.12.044) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 6 Phase diagram of the critical distance (xcr) where the volume fraction of cells reaches the maximum close packing (φw ∼ φmax ∼ 0.6) as a function of the initial volume fraction φo and channel location. (A) Low permeation flux (A = 10%). (B) High permeation flux (A = 70%). At a critical value of initial volume fraction, the maximum close packing is reached along the length of the channel, causing excess cell buildup (caking) and hindering cell capture (white dotted line). Devices were operated in the optimum regime (φo = 0.1, Qin = 6 mL/h, A = 70%) to maximize throughput without excess cell buildup (red line). Biophysical Journal 2012 102, 721-730DOI: (10.1016/j.bpj.2011.12.044) Copyright © 2012 Biophysical Society Terms and Conditions