Isobaric Labeling Proteomics Allows a High-Throughput Investigation of Protein Corona Orientation.

The formation of the biomolecular corona represents a crucial factor in controlling the biological interactions and trafficking of nanomaterials. In this context, the availability of key epitopes exposed on the surface of the corona, and able to engage the biological machinery, is important to define the biological fate of the material. While the full biomolecular corona composition can be investigated by conventional bottom-up proteomics, the assessment of the spatial orientation of proteins in the corona in a high-throughput fashion is still challenging. In this work, we show that labeling corona proteins with isobaric tags in their native conditions and analyzing the MS/MS spectra of tryptic peptides allow an easy and high-throughput assessment of the inner/outer orientation of the corresponding proteins in the original corona. We put our results in the context of what is currently known of the protein corona of graphene-based nanomaterials. Our conclusions are in line with previous data and were confirmed by in silico calculations.