title: Bovine Serum Albumin Adsorption on TiO2Colloids: The Effect of Particle Agglomeration and Surface Composition.
abstract: Protein adsorption at nanostructured oxides strongly depends on the synthesis conditions and sample history of the material investigated. We measured the adsorption of bovine serum albumin (BSA) to commercial Aeroxide TiO2P25 nanoparticles in aqueous dispersions. Significant changes in the adsorption capacity were induced by mild sample washing procedures and attributed to the structural modification of adsorbed water and surface hydroxyls. Motivated by the lack of information about the sample history of commercial TiO2nanoparticle samples, we used vapor-phase-grown TiO2nanoparticles, a well-established model system for adsorption and photocatalysis studies, and performed on this material for the first time a systematic and quantitative BSA adsorption study. After alternating vacuum and oxygen treatment of the nanoparticle powders at elevated temperatures for surface purification, we determined size distributions covering both the size of the individualized nanoparticles and nanoparticle agglomerates using transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) in an aqueous dispersion. Quantitative BSA adsorption measurements at different pH values and thus variable combinations of surface-charged proteins and TiO2nanoparticles revealed a consistent picture: BSA adsorbs only at the outer agglomerate surfaces without penetrating the interior of the agglomerates. This process levels at coverages of single monolayers, which resist consecutive simple washing procedures. A detailed analysis of the protein-specific IR amide bands reveals that the adsorption-induced protein conformational change is associated with a decrease in the helical content. This study underlines that robust qualitative and quantitative statements about protein adsorption and corona formation require well-documented and controllable surface properties of the nanomaterials involved.
authors.affiliation: Department of Chemistry and Physics of Materials, Paris Lodron University of Salzburg , Jakob-Haringer-Strasse 2a, A - 5020 Salzburg, Austria.
authors.forename: Augusto
authors.initials: A
authors.lastname: Márquez
authors.affiliation: Department of Chemistry and Physics of Materials, Paris Lodron University of Salzburg , Jakob-Haringer-Strasse 2a, A - 5020 Salzburg, Austria.
authors.forename: Thomas
authors.identifier: 0000-0002-2062-5193
authors.initials: T
authors.lastname: Berger
authors.affiliation: Department of Chemistry and Physics of Materials, Paris Lodron University of Salzburg , Jakob-Haringer-Strasse 2a, A - 5020 Salzburg, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Feinle
authors.affiliation: Department of Chemistry and Physics of Materials, Paris Lodron University of Salzburg , Jakob-Haringer-Strasse 2a, A - 5020 Salzburg, Austria.
authors.forename: Nicola
authors.initials: N
authors.lastname: Hüsing
authors.affiliation: Department of Molecular Biology, Paris Lodron University of Salzburg , Hellbrunnerstrasse 34/III, A - 5020 Salzburg, Austria.
authors.forename: Martin
authors.identifier: 0000-0001-5416-085X
authors.initials: M
authors.lastname: Himly
authors.affiliation: Department of Molecular Biology, Paris Lodron University of Salzburg , Hellbrunnerstrasse 34/III, A - 5020 Salzburg, Austria.
authors.forename: Albert
authors.identifier: 0000-0002-7034-9860
authors.initials: A
authors.lastname: Duschl
authors.affiliation: Department of Chemistry and Physics of Materials, Paris Lodron University of Salzburg , Jakob-Haringer-Strasse 2a, A - 5020 Salzburg, Austria.
authors.forename: Oliver
authors.initials: O
authors.lastname: Diwald