Fig. 7. Schematic representation of the proposed model for the formation of hard and soft coronae.

a Three types of SC proteins were identified by LC–MS/MS analysis after the click reaction. The SC proteins are mainly the same as HC proteins, while the process of hardening does not define the protein corona composition, but rather changes the binding strength of the already-formed SC. b Hardening of HC through either more incubation time or cross-linking SC by using a click reaction prepares a biologically relevant residence time for corona proteins, and reduces the exchange of corona proteins with medium proteins and accessibility of the surface of NPs. The net effect of specific and nonspecific associations will determine the fate of nanoparticles in contact with cells. CA cell association.