Mouse splenocytes (approximately

105 cells per sample) containing CD4 T, CD8 T, natural killer (NK), and natural killer T (NKT) cells were prepared from the spleen of C57BL/6/mice (Nara Biotech, Seoul, South Korea) [22]. Prior to introducing the cell suspension in PBS solution onto the QNPA substrates (0.7 cm × 0.7 cm), the cell population (Figure 1c) with a final volume of approximately 30 μl was first reacted with biotin anti-mouse CD4 antibody and incubated at 4°C for 20 min. The cell suspension containing T cells and other cells pre-reacted with biotin anti-mouse CD4 antibody was then introduced on the STR-functionalized QNPA substrates. Following 20 min of incubation at 4°C in a refrigerator, where the CD4 T cells were in a very early stage of cell adhesion on the QNPA substrates, unbound cells were removed by rinsing with PBS solution. This step was VX-689 purchase repeated at least five times for 10 min on a 2D rocker to completely

remove nonspecifically unbound cells from the QNPA substrates (third image in Figure 1c). Our experiments were focused on targeted CD4 T cell adhesion on STR-functionalized QNPA substrates at a very early stage of cell adhesion (<20 min). To examine the morphologies of the captured CD4 T cells bound on STR-conjugated QNPA substrates, SEM observation was performed. For the SEM observation of the captured cells on QNPA substrate, a series of cell-fixing processes are required as follows. The T cells were first fixed with 4% GA in the refrigerator for nearly 2 BIBF 1120 manufacturer h, followed by a post-fix process using 1% osmium tetroxide for 2 h. The T cells were then dehydrated through a series of ethanol concentrations (25%, 50%, 75%, 95%, and 100%) and slowly dried at vacuum-connected desiccators for 24 h [21, 23, 24]. According to a previous report, the average conventional fixed material, after all steps of preservation, retained 72%

of its initial size [25]. Once the samples were dry in the desiccators, the surface-bound T cells were sputter-coated with VX-680 clinical trial platinum before the SEM measurement was performed. Figure 1 Schematic diagram of QNPA fabrication and separation processes. (a) Schematic diagram outlining the fabrication of quartz nanopillar arrays (QNPAs) where two different sizes of PS were presented for specific example. (b) Surface functionalization including APTES, GA, and STR reactions of QNPAs on a quartz substrate. (c) Schematic diagram of specific CD4 T cell separation process from introduced cell suspension containing CD4 T, CD8 T, NK, and NKT cells from primary mouse splenocytes. Results and discussion Figure 2a,b shows SEM images (top, tilt, and enlarged views) of CD4 T cells bound on four different sizes of STR-functionalized QNPA substrates. The diameters of QNPA using four PS NPs (200, 300, 430, and 750 nm in diameter) were approximately 100, 200, 300, and 450 nm, respectively, as determined by SEM.