Cell-repellant dextran coatings of porous titania using mussel adhesion chemistry.

The resistance of bioceramics against non-specific adsorption of serum proteins is critical for a wide range of biomedical applications. Some polysaccharides serve as natural protein-resistant molecules in extracellular matrices; however, the stable adhesion of polysaccharides to ceramic biomaterials in an aqueous solution is very challenging because chemical linkages at organic/inorganic interfaces are susceptible to hydrolytic degradation. Here, a catechol-grafted dextran, which strongly binds to titania (TiO2 ) in an aqueous milieu to effectively suppress cell adhesion through anti-fouling activity against non-specific protein adsorption, is introduced. Catechol is conjugated approximately to 6.7 mol% of glucose units of dextran via a carbamate ester linkage, corresponding to roughly three catechols per dextran chain having an average molecular weight of 6 kDa. Multivalent interactions of catechols with a titanium atom, enabled by the graft-type structure, provide a very stable coating of dextran on this inorganic surface. The adhesion of HeLa cells on the dextran-coated titania surface is reduced by 2.4-fold compared to that on a pristine titania surface. These results suggest that the graft-type incorporation of a small number of catechol moieties along a dextran backbone is an effective means of producing a stable anti-fouling interface on inorganic biomaterials in an aqueous environment.