title: Bovine Serum Albumin Adsorption at a Silica Surface Explored by Simulation and Experiment.
abstract: Molecular details of BSA adsorption on a silica surface are revealed by fully atomistic molecular dynamics (MD) simulations (with a 0.5 μs trajectory), supported by dynamic light scattering (DLS), zeta potential, multiparametric surface plasmon resonance (MP-SPR), and contact angle experiments. The experimental and theoretical methods complement one another and lead to a wider understanding of the mechanism of BSA adsorption across a range of pH 3-9. The MD results show how the negatively charged BSA at pH7 adsorbs to the negatively charged silica surface, and reveal a unique orientation with preserved secondary and tertiary structure. The experiments then show that the protein forms complete monolayers at ∼ pH6, just above the protein's isoelectric point (pH5.1). The surface contact angle is maximum when it is completely coated with protein, and the hydrophobicity of the surface is understood in terms of the simulated protein conformation. The adsorption behavior at higher pH > 6 is also consistently interpreted using the MD picture; both the contact angle and the adsorbed protein mass density decrease with increasing pH, in line with the increasing magnitude of negative charge on both the protein and the surface. At lower pH < 5 the protein starts to unfold, and the adsorbed mass dramatically decreases. The comprehensive picture that emerges for the formation of oriented protein films with preserved native conformation will help guide efforts to create functional films for new technologies.
authors.affiliation: Department of Chemical and Process Engineering, University of Strathclyde , James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, U.K.
authors.forename: Karina
authors.identifier: 0000-0002-2357-2111
authors.initials: K
authors.lastname: Kubiak-Ossowska
authors.affiliation: J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Science (PAS) , Niezapominajek 8, 30-239 Cracow, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Tokarczyk
authors.affiliation: J. Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Science (PAS) , Niezapominajek 8, 30-239 Cracow, Poland.
authors.forename: Barbara
authors.identifier: 0000-0002-2445-7318
authors.initials: B
authors.lastname: Jachimska
authors.affiliation: Department of Chemical and Process Engineering, University of Strathclyde , James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, U.K.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Mulheran
mesh_terms: D000327:Adsorption; D000818:Animals; D002417:Cattle; D000067493:Dynamic Light Scattering; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D011487:Protein Conformation; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D055672:Static Electricity; D020349:Surface Plasmon Resonance; D013499:Surface Properties
chemical_list: D012710:Serum Albumin, Bovine; D012822:Silicon Dioxide