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.