To understand better the release mechanism of the EVs and the effect of the solute size on the diffusion parameters, Fluorescent Recovery After Photobleaching (FRAP) measurements were conducted using FITC-dextrans of varying molecular weights (4, 70, and 500 kDa). The distribution of these dextrans within the hydrogel and at the gel-solution interphase are shown in Figure , with two-dimensional images taken in fluorescence and merged (brightfield and fluorescence) channels. Additionally, 3D images constructed through z-stack analyses illustrated dextran distribution inside the hydrogel that shows each dextran probe is homogenously distributed in the hydrogel matrix which is crucial to interpret the diffusion data acquired by FRAP (Figure ). The diffusion coefficients determined via FRAP were 232±12, 64.6±0.5, and 36.7±2.7 µm²/s for 4, 70, and 500 kDa dextrans, respectively, with reported hydrodynamic diameters of 1.4, 6.0, and 15.9 nm in aqueous solution.