I3 filter cube

Ethylenediamine (EDA, ≥99.5%) and sodium chloride (NaCl, ≥99.5%) were purchased from Sigma-Aldrich (Sigma-Aldrich Chemie BV, Zwijndrecht, The Netherlands) to prepare 50 mM EDA ( pH 7.0) buffer solutions without NaCl and with 0.3 M, 0.6 M, and 0.9 M NaCl. 1 : 100 diluted Source 15Q (S15Q, ∅ 15 µm, monodisperse, rigid, polystyrene/divinyl benzene beads with an optimized pore size distribution; GE Healthcare Life Sciences, GE Healthcare Europe GmbH, Eindhoven, The Netherlands) suspension and 6.0 g L -1 of albumin-fluorescein isothiocyanate conjugate (FITC-BSA, Sigma-Aldrich Chemie BV, Zwijndrecht, The Netherlands) solution were prepared in each buffer solution for obtaining adsorption isotherms of FITC-BSA at 0.0 M, 0.3 M, 0.6 M, and 0.9 M NaCl. The fluorescence images of the 18 reactors were acquired by using a Leica I3 filter cube (excitation: BP 450-490 nm; emission: LP 515 nm).

For the quantification of the number of S15Q particles in 200 µl volume, we counted the number of particles in 1 µl of 1 : 1000 diluted S15Q suspension by using microscopy images of the suspension on a microscope slide, and obtained the number of 165 ± 15 (n = 3). 60 µl of 1 : 10 diluted S15Q suspensions were prepared in 45 wells in a MultiScreen Solvinert filter plate (96-well filter plate with a hydrophobic PTFE membrane with a pore size of 0.45 µm, Merck Millipore Co., Millipore BV, Amsterdam-Zuidoost, The Netherlands) and the aqueous suspensions were filtered into a 96 well plate (Corning Inc., Corning Life Sciences BV, Amsterdam, The Netherlands) by centrifugation at 300 rpm for 5 minutes to separate off the S15Q particles. Then 200 µl of FITC-BSA solution was loaded into 90 wells, 45 wells with S15Q and 45 wells without S15Q, in the filter plate and incubated at room temperature for 2 hours in a shaking incubator. After the incubation, the FITC-BSA solution was filtered into a new 96-well plate by centrifugation at 300 rpm for 5 minutes and loaded into a microchannel. The width and height of the microchannel were 100 µm and 24 µm, respectively (the design of the microchannel is shown in ESI Fig. S2 †). The fluorescence intensities of FITC-BSA in solutions were obtained by using a Leica I3 filter cube (excitation: BP 450-490 nm; emission: LP 515 nm).

One hundred micromolars of resorufin (Sigma-Aldrich Chemie N.V., Zwijndrecht, The Netherlands) solution was introduced into the drug solution inlet while the cell medium inlet for cell medium was filled used to introduce with Milli-Q water. After mixing the solutions in six independent reactors (Fig. 1C) for 2 min, fluorescent images were acquired for the 6 reactors using a Leica I3 filter cube (excitation: BP 450-490 nm; emission: LP 515 nm). Source 15Q ( 15 m particles based on rigid polystyrene /divinyl benzene polymer matrix, GE Healthcare Europe GmbH, Eindhoven, The Netherlands) to be used as a surrogate for cells, were diluted to a 1:1000 ratio in Milli-Q water (500 000 beads/mL) for testing the particle capture and isolation in individual incubation chambers.