Figure 5.
Anti-CD63 antibody on a Super Epoxy 3 slide to capture extracellular vesicles. (a) Printed anti-CD63 FITC-labeled antibody after two washing steps to validate the washing protocol. The difference in antibody density within a single spot as well as between spots was clearly visible as indicated with white arrows 1, 2, and 3. (b) Fluorescent image of the preconcentrated EVs in the microchannel from an initial concentration of 9.3 × 107 particles/1 mL during ICP for 21 min at 45 V/cm (ND 1 filter and 1 s exposure time). The fluorescently labeled EVs bound on the circular spots of the printed anti CD-63 antibody solution are indicated with white arrows 1, 2 and 3. A second fluorescent plug was visible in the upper region of the microchannel representing the unbound free dye that was separated from the EVs during ICP due to its higher electrophoretic mobility. (c) After turning off the voltage at 30 min, the pressure-driven flow from the buffer solution washed away any unbound EVs and free dye into the sample reservoir. The fluorescently labeled EVs bound on the circular spots of the printed anti CD-63 antibody are highlighted with white arrows 1, 2, and 3. The difference in the amount of bound EVs on the antibody spots can be explained by the variation of the antibody density in the spots, as shown in (a).