Fig. 2.

Control of PSI microsphere characteristics during the fabrication process. A. Size of microspheres can be controlled during the fabrication process as a function of time. BSA-only–containing template microspheres were fabricated and allowed to sit for various times immediately after initial vortexing. Size was measured via differential interference contrast (DIC) microscopy image analysis using ImageJ. B. A representative DIC microscopy image used for size analysis of PSI-containing microspheres after chelation, BSA:PSI ratio 500:1 and initial particle incubation of ~5 s. C. A representative image analysis showing the particles analyzed using ImageJ macros for size analysis measurement. All white particles are those automatically detected by the software and analyzed for shape and size. Samples here and analyzed in panel D contain only BSA protein. D. A histogram showing the size distribution of the particles in C including other images of the same sample, n = 576; bin size = 0.25 μm. E. The inclusion of PSI in template microspheres at increasing concentration (lower BSA:PSI ratios) leads to decreased diameter of microspheres after chelation. The diameter of particles was measured using DLS. The data represent 10 different full measurements of DLS of each sample, each to an N = 1,000,000.