FCS curves at the different time points were fitted using a two-component fit to account for both diffusing species (loaded nanogels and released OG-BSA). Further, a correction was included to account for the disproportional effect of bright slow diffusing species (loaded nanogels) compared to the less bright free OG-BSA. We propose herein (see Materials and Methods in SI) to simply combine the fraction of free OG-BSA (directly from the twocomponent fit) with the decrease in the number of cargo for the remaining nanogels (via CPP), which is a second indicator for OG-BSA release (number of proteins per nanogel is decreasing). This correction is necessary because nanogels with several loaded proteins overlap with the free protein signal, as demonstrated in the literature for mixtures of differently sized nanoparticles of varying brightness. This finally yielded the percentage of free OG-BSA and allowed us to further calculate the cumulative release profile over time (Figure ). A clear difference between 90 nM MMP-7-triggered release and diffusion-based profiles was detected, whilst the release profile in the presence of 9 and 0.9 nM MMP-7 gave intermediate results as expected for an enzyme-triggered release. This successful enzymetriggered release profile justifies the further study of these copolymer libraries using therapeutic cargo and studying release behaviour at various temperatures, accompanied by corresponding delivery data at the cell and tissue level but this is beyond the scope of this paper. It is also clear that MMP-7 triggered release profiles will vary significantly in vivo compared to the in vitro data, due to a much higher level of environmental complexity that will cause differences in cross-linker degradation and hence release. Reasons for these differences include the presence of other substrates and specific cofactors, as well as continuous turn-over of enzymes. Release studies in more complex environments, including in the presence of cells and tissue, are needed in the future to choose an optimal copolymer system for the delivery of a specific drug for a chosen disease that involves upregulation of MMP enzymes at the disease site. Simply changing the peptide cross-linker sequence will further allow application of our nanogel platform using other enzymes as triggers, as relevant in specific diseases.