To better assess the release kinetics of EVs from the hydrogel matrix and to make fluorescent microscopy possible, EVs were fluorescently labeled. This was achieved by covalently attaching a fluorescent dye, carboxyfluorescein succinimidyl ester (CFSE), to the protein cargos of the EVs. Such fluorescence detection of released CE-EVs from hydrogel can provide a more accurate quantitative assessment compared to NTA as shredded polypeptide fragments released from the crosslinked hydrogel can potentially appear as particles during NTA analysis, leading to misinterpretation of the data.