Regarding the PEG block, one of the conformations has an extended PEG block (cluster 2) and the other one (cluster 3) a collapsed PEG block. In a previous study, we investigated the dynamics of PEG blocks at the interface of polymeric NPs, showing they exist in highly extended conformations as well as lying along the interface of the NP. The two conformations of these PEG-PLGA block copolymers identified at the core-corona interface, which are present in almost equal measures, are consistent with the contracted and extended states of the PEG blocks previously observed in those atomistic simulations. Therefore, the polymers take specific conformations as a result of their location within the NP, as was previously reported in our atomistic-level studies, where we have shown that block copolymers adopt location-specific conformations within micelles of various polymer chemistries and topologies. (a) (b) The enrichment takes into account the relative cluster population, such that an enrichment value greater than 1 means the peptides have a tendency to interact with that polymer conformation, an enrichment value less than 1 suggests that there is a depletion of the polymers in that cluster around the peptide and a value of 1 means that the peptide and the polymers from that cluster interact randomly. In (b), there is a snapshot showing a peptide interacting with the most preferential polymer cluster, cluster 4. In this snapshot, PLGA is colored pink, PEG is light blue, the peptide is orange and water is navy blue. The error bar of Cluster 3 in (b) is colored in gray due to poor statistics for this cluster, as there are not many interactions between the peptides captured inside the core and this cluster. The theoretical background for this calculation can be found in the SI.