Figure 2.

(a) Architecture of the SL microfluidic device used in this work. The device has two inlets, one for the solution containing the probe (dye molecule), and the other for the sample solution (contains the aggregating protein). When the streams converge, the dye can start to diffuse into the protein stream and hence bind the aggregating protein that becomes labeled (yellow). The fluorescence intensity is recorded further downstream where the diffusion of the dye into the protein stream has resulted in complete binding. (b) A fluorescence microscopy image of the measurement area. (c) Seeded ex situ aggregation curves obtained at 0.03 mg mL⁻¹ (blue triangles) and 0.05 mg mL⁻¹ (red circles) of bovine insulin using the device in (a) together with manually performed control assays at the same concentrations (yellow squares and yellow circles, respectively; average of n = 3 repeats). To see this figure in color, go online.