Binding of polystyrene and carbon black nanoparticles to blood serum proteins

CONTEXT: Once inhaled, nanoparticles (NP) deposit on the lung surface and have first contact with the epithelial lung lining fluid (ELF) rich in proteins, which may bind to NP. OBJECTIVE: In this study, we investigate the parameters that influence the binding between NP and proteins. MATERIALS AND METHODS: We used the proteins albumin, transferrin (TF), and apolipoprotein A-1 (all known as proteins from ELF) and different NP (polystyrene NP with negative, positive, and neutral surface coatings, Printex G and Printex 90) as models. RESULTS: In all cases, a linear correlation of the added NP amount and the amount of bound proteins was found and was described quantitatively by binding indices. Bovine serum albumin (BSA), TF, and apo A-1 were bound to the largest extent to hydrophobic NP, which shows the extraordinary importance of the NP's surface properties. DISCUSSION: The binding index indicates the relevance of primary particle size and surface properties, including hydrophobicity. CONCLUSION: Size and surface modifications of NP determine their protein binding. Our results suggest that the formation of conjugates of BSA, TF, and Apo A-1 with NP may play an important role in their translocation across the air-blood-barrier and subsequent biokinetics.