Characterizing Protein Corona Formation on Polystyrene Nanoparticles Using Single-Molecule Analysis

It is well known that nanoparticles in biological media form a protein coating, called a protein corona. The corona has been hypothesized to be one of the most important factors in determining a nanoparticle’s fate and effect on cells. Here we have used fluorescence correlation spectroscopy (FCS), a non-invasive, single-molecule analysis technique, to characterize the adsorption of fluorescently labelled human transferrin and bovine serum albumin onto 50nm diameter polystyrene (PS) beads. The size of the corona was found to increase with protein concentration, with evidence of bilayer corona formation shown in both transferrin and albumin. The time span of corona formation was 120 minutes in transferrin and 180 minutes in albumin. Albumin coated PS beads showed significantly improved salt stability characteristics, an important result for medical potential. Results from this study will inform future studies of protein corona formation on nanoceria particles, specifically for drug delivery across the blood-brain barrier via transferrin-receptor mediated endocytosis.