Conformation change of bovine serum albumin induced by bioactive titanium metals and its effects on cell behaviors

The conformation change of bovine serum albumin (BSA) induced by bioactive titanium surfaces, including acid‐alkali‐treated titanium (AA‐Ti) and alkali–heat‐treated titanium (AH‐Ti), was studied, and its effects on the activity of MC3T3‐E1 cell were evaluated. Pure titanium metal (P‐Ti) was used as control. The AA‐Ti could adsorb more BSA on its surface than AH‐Ti and P‐Ti. The α‐helix part of the protein adsorbed on P‐Ti has weakly decreased compared with native BSA, and it dramatically decreased on AA‐Ti and AH‐Ti. The β‐sheet segment of proteins adsorbed on P‐Ti and AH‐Ti had obviously increased. Much more tryptophan residues were exposed after the protein conformation changed when it interacted with AH‐Ti, and some tryptophan residues were enveloped after it interacted with AA‐Ti and P‐Ti. AA‐Ti has more tryptophan residues enveloped than P‐Ti. All titanium surfaces induced tyrosine residues exposed, especially for the P‐Ti. The higher ratio of COO⁻/NH₃⁺ for the proteins on P‐Ti and AA‐Ti indicated an orientation of proteins on P‐Ti and AA‐Ti, which makes more COO⁻ exposed. The lower ratio of COO⁻/NH₃⁺ on AH‐Ti indicates that more NH₃⁺ is exposed on its surface. The cell proliferation ability on different treated titanium surfaces coated with BSA followed by the order: P‐Ti > AA‐Ti > AH‐Ti, which indicated that the protein conformation change on different bioactive titanium surfaces has great effect on the cell activity. Our results showed that the different biological response of bioactive titanium metals might depend on the protein conformation change induced by the surface structure. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1053–1062, 2014.