Identification of serum proteins bound to industrial nanomaterials.

Nanoparticles (NPs) are decorated with proteins and other biomolecules when they get into contact with biological systems. The presence of proteins in cell culture medium can therefore have effects on the biological outcome in cell-based tests. In this study, the manufactured nanomaterials silicon dioxide (SiO(2)), titanium dioxide (TiO(2)), iron-III-oxide (Fe(2)O(3)), and carbon black (CB) were used to study their interaction with single proteins from bovine and human plasma (albumin, fibrinogen and IgG) as well as with complete human serum. The protein binding capacity of the material was investigated and 1D gel electrophoresis was used to separate the bound proteins and to identify the bands by matrix-assisted laser desorption/ionisation-time-of-flight (MALDI-TOF) mass spectrometry. We found that the NP surface chemistry had a great impact on the amount of bound protein with distinct ligands for each of the tested particles. The hydrophobic CB NPs bound much more protein than the hydrophilic metal oxide NPs. Among the single proteins investigated, fibrinogen showed the strongest affinity for SiO(2), TiO(2) and CB NPs. The identified proteins from human serum adsorbed to these NPs were very different. Only apolipoprotein A1 was found to be adsorbed to all NPs. These studies will help to explain the different degree of biological responses observed after in vitro exposure of cells in the absence or presence of serum and might also support the interpretation of in vivo experiments were NPs come directly into contact with blood plasma.