Density Functional Theory Study of Catechol Adhesion on Silica Surfaces

It has been speculated that the catechol (1,2-dihydroxybenzene) functionality of marine mussels is responsible for its strong and versatile adhesion on various wet surfaces. To elucidate features of this adhesion, we performed a periodic density functional theory calculation for catechol adsorption on silica surfaces. We obtained its binding energy and geometry on two representative hydroxylated surfaces of cristobalite, which mimic amorphous silica. Catechol strongly adhered to both surfaces by making three or four hydrogen bonds. Catechol achieved versatility in adhesion via torsion of its hydroxyls. The binding energy of catechol, which amounts to 14 kcal/mol, was larger than that of water, irrespective of the surface. With the inclusion of dispersion interaction, the binding energy of catechol further increased up to 33 kcal/mol, and its preferential adsorption over water became evident. Both the hydroxyls and phenylene ring of catechol contribute to its strong adhesion due to hydrogen bonds and dispersion.