Adhesion of mussel foot protein-3 to TiO2 surfaces: the effect of pH.

TitleAdhesion of mussel foot protein-3 to TiO2 surfaces: the effect of pH.
Publication TypeJournal Article
Year of Publication2013
AuthorsYu, J, Wei, W, Menyo, MS, Masic, A, Waite, JH, Israelachvili, JN
Date Published2013 Apr 8
KeywordsAdhesiveness, Animals, Bivalvia, Dihydroxyphenylalanine, Hydrogen-Ion Concentration, Oxidation-Reduction, Prostheses and Implants, Proteins, Spectrum Analysis, Raman, Titanium

The underwater adhesion of marine mussels relies on mussel foot proteins (mfps) rich in the catecholic amino acid 3,4-dihydroxyphenylalanine (Dopa). As a side chain, Dopa is capable of strong bidentate interactions with a variety of surfaces, including many minerals and metal oxides. Titanium is among the most widely used medical implant material and quickly forms a TiO2 passivation layer under physiological conditions. Understanding the binding mechanism of Dopa to TiO2 surfaces is therefore of considerable theoretical and practical interest. Using a surface forces apparatus, we explored the force-distance profiles and adhesion energies of mussel foot protein 3 (mfp-3) to TiO2 surfaces at three different pHs (pH 3, 5.5 and 7.5). At pH 3, mfp-3 showed the strongest adhesion force on TiO2, with an adhesion energy of ∼-7.0 mJ/m(2). Increasing the pH gives rise to two opposing effects: (1) increased oxidation of Dopa, thus, decreasing availability for the Dopa-mediated adhesion, and (2) increased bidentate Dopa-Ti coordination, leading to the further stabilization of the Dopa group and, thus, an increase in adhesion force. Both effects were reflected in the resonance-enhanced Raman spectra obtained at the three deposition pHs. The two competing effects give rise to a higher adhesion force of mfp-3 on the TiO2 surface at pH 7.5 than at pH 5.5. Our results suggest that Dopa-containing proteins and synthetic polymers have great potential as coating materials for medical implant materials, particularly if redox activity can be controlled.

Alternate JournalBiomacromolecules
PubMed ID23452271
PubMed Central IDPMC3635841
Grant ListR01 DE018468 / DE / NIDCR NIH HHS / United States
R01-DE018468 / DE / NIDCR NIH HHS / United States