The release profile was fitted to a mathematical 1D-diffusion model, To further investigate the hydrogel network structure and its influence on EV-distribution and diffusion within the hydrogel network, fluorescently labeled EVs and silica nanoparticles (SiNPs) of similar sizes were encapsulated in the hydrogel. Several aggregates with significantly bigger sizes can be seen in the three-dimensional images (Figure ). This aggregation can be induced by the interaction with the hydrogel matrix since neither the NTA nor the fluorescent microscopy in PBS showed similar structures. However, the majority of both EVs and SiNPs were found to be evenly distributed within the hydrogel and not released into the surrounding solution within the microscopy time scale (Figure ).