Free dye, OG-BSA and OG-BSA incorporated in nanogels can already be distinguished clearly in the fitted autocorrelation curves (Figure ). When calculating the corresponding diffusion times (τD) and hydrodynamic diameters (DH) the size difference between the diffusing species was obtained (Figure ). In the case of the nanogel measurements, the diffusing species correspond to the nanogel hydrodynamic diameter obtained in other measurements (Figure and Figure ), which indicates successful incorporation of OG-BSA. Comparing the signal intensity per nanogel (counts per particle, CPP in kHz) with that of free OG-BSA, the number of loaded OG-BSA per single nanogel was determined and shows that multiple protein cargos were loaded per nanogel (Figure ). Release studies were performed in triplicate by incubating OG-BSA loaded nanogels (batches A-C) with various MMP-7 concentrations in a physiologically relevant nanomolar range. FCS curves recorded at different time points in the presence or absence of MMP-7 revealed the release kinetics (Figure , Figure ). This allowed us to compare diffusion-driven release (non-specific release from the nanogels over time) to MMP-7 triggered release.