Proteomic Analysis and Molecular Dynamics Simulation of Riboflavin-Coated Superparamagnetic Iron Oxide Nanoparticles Reveal Human Serum-Derived Protein Coronas: Implications as Magnetic Resonance Imaging Contrast Agents

Superparamagnetic iron oxide nanoparticles (SPIONs) havebeen increasinglyused as nanomedicine platforms due to their exceptional magnetic properties,which emerged from their nanoscopic sizes. Recently, SPIONs with ariboflavin (Rf)-citrate ligand were developed and showed increasedinternalization in breast cancer cells, with exceptional propertiesas T (2) contrast agents for magnetic resonanceimaging (MRI). The interactions of the Rf-coated SPIONs with proteinsfrom fetal bovine serum (FBS) were previously characterized to understandhow the nanoparticles will interact with biomolecules. To closer mimicthe human biological environments, human serum (HS) has been suggestedas a better model. Therefore, in this work, protein coronas of bare,citrate-coated, and Rf-coated SPIONs formed with HS were studied byproteomic analysis to identify and quantify the nanoparticle-proteininteraction. The results were compared with the FBS-derived coronasto understand the differences in the protein corona formation fromdifferent serum origins. Furthermore, the interactions of the SPIONswith riboflavin carrier protein (RCP), which is a target protein forthe Rf-SPIONs, were also studied. The overall physical propertiesof the corona proteins were similar between the FBS and HS groups,but some specific homologous proteins interacted differently. TheRCP was found to bind more to the citrate-coated SPIONs than the Rf-coatedone. The outcome could be explained by molecular dynamics simulation,where the orientation of the Rf ligand did not favor the binding withRCP. The simulation results also showed the influence of surface hydrophilicityof the SPIONs on the RCP interaction. The combined data from proteomicand simulation analyses suggested a way to improve the Rf ligand toenhance the interaction with RCP and reduce the interactions withthe serum proteins, which could enhance the specific cellular interactionsand improve the Rf-SPIONs as MRI contrast agents for breast cancer.