Stealth effect of biomolecular corona on nanoparticle uptake by immune cells.

When injected in a biological milieu, a nanomaterial rapidly adsorbs biomolecules forming a biomolecular corona. The biomolecular corona changes the interfacial composition of a nanomaterial giving it a biological identity that determines the physiological response. Characterization of the biomolecular structure and composition has received increasing attention mostly due to its detrimental impact on the nanomaterial's metabolism in vivo. It is generally accepted that an opsonin-enriched biomolecular corona promotes immune system recognition and rapid clearance from circulation. Here we applied dynamic light scattering and nanoliquid chromatography tandem mass spectrometry to thoroughly characterize the biomolecular corona formed around lipid and silica nanoparticles (NPs). Incubation with human plasma resulted in the formation of NP-biomolecular coronas enriched with immunoglobulins, complement factors, and coagulation proteins that bind to surface receptors on immune cells and elicit phagocytosis. Conversely, we found that protein-coated NPs were protected from uptake by macrophage RAW 264.7 cells. This implies that the biomolecular corona formation provides a stealth effect on macrophage recognition. Our results suggest that correct prediction of the NP's fate in vivo will require more than just the knowledge of the biomolecular corona composition. Validation of efficient methods for mapping protein binding sites on the biomolecular corona of NPs is an urgent task for future research.