Microfluidic Trapping of Antibody-secreting Cells

The development of antibody-based drugs typically begins with the isolation and screening of thousands of antibody-secreting cells, often requiring 4-6 weeks to identify only 1-10 cell lines of interest. We are developing a novel immunobiosensing device to afford direct and rapid assessment of the antibody production of each of thousands of living cells captured on a single slide. Each cell shall be trapped near a designated surface plasmon-resonant nanohole array immunobiosensor to detect the binding of the cell’s secreted antibodies to an immobilized target antigen. This paper presents arrays of single-cell traps consisting of concave hydrodynamic structures and inset microwells. Each design is fabricated using either SU-8 photoresist or poly(dimethyl siloxane) (PDMS) and then tested using polystyrene microspheres and 17/9 mouse B cell hybridoma cells. Although we find that PDMS adheres more strongly to our substrates than SU-8, we also find that channels fabricated in PDMS are wider than expected and thus fail to limit cellular passage. The hydrodynamic tests agree with the predictions of finite element modeling using COMSOL Multiphysics. We find that the hydrodynamic designs featuring concave traps inset into spirals and serpentine bends capture cells more efficiently than our other hydrodynamic designs. Testing also verifies the functionality of our microwell traps, with 5-20 cells/well trapped following a 10 min settling time. Moreover, untrapped cells beyond the microwells are removed via peristaltic pumping, with minimal trapped cell displacement. Furthermore, 4-24 hr trapped-cell incubations verify the biocompatibility of each of our fabricated designs, provided that a Cr-free substrate is used.