(407g) The Adhesion Mechanism of Mussel Adhesive Protein-3 to TiO2 Surface

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. TiO2 is one of the most common used medical implants materials. Studying the binding mechanism of dopa to TiO2 surface is therefore of theoretical and practical interests. Using a surface forces apparatus, we explored the force distance profile and the adhesion energy of mussel foot protein 3 (mfp-3) to TiO2 surface in three different pHs (pH3, 5.5, and 7.5). At pH3, mfp-3 showed the strongest adhesion force on TiO2, with an adhesion energy of ~ -7.0 mJ/m². Increasing the pH gives rise to two opposing effects: it causes the oxidation of dopa, which eliminates the dopa adhesion; meanwhile, higher pH increases the binding affinity of dopa-Ti coordination bond, leading to the further stabilization of the dopa group and an increase of adhesion force. The two competing effects give rise to a higher adhesion force of mfp-3 on TiO2 surface at pH 7.5 than the adhesion force measured at pH 5.5. Our results suggest that dopa containing proteins and synthetic polymers have a great potential to be used as coating materials for medical implants.