Mass spectrometry-based top-down proteomics in nanomedicine: proteoform-specific measurement of protein corona

Conventional mass spectrometry (MS)-based bottom-up proteomics (BUP) analysis of protein corona [i.e., an evolving layer of biomolecules, mostly proteins, formed on the surface of nanoparticles (NPs) during their interactions with biomolecular fluids] enabled nanomedicine community to partly identify the biological identity of NPs. Such an approach, however, fails pinpoint the specific proteoforms--distinct molecular variants of proteins, which is essential for prediction of the biological fate and pharmacokinetics of nanomedicines. Recognizing this limitation, this study pioneers a robust and reproducible MS-based top-down proteomics (TDP) technique for precisely characterizing proteoforms in the protein corona. Our TDP approach has successfully identified hundreds of proteoforms in the protein corona of polystyrene NPs, ranging from 3-70 kDa, revealing over 20 protein biomarkers with combinations of post-translational modifications, signal peptide cleavages, and/or truncations--details that BUP could not fully discern. This advancement in MS-based TDP offers a more comprehensive and exact characterization of NP protein coronas, deepening our understanding of NPs biological identities and potentially revolutionizing the field of nanomedicine.