Biomimetic dextran coatings on silicon wafers : thin film properties and wetting

There has been much recent interest in polysaccharide coatings for biotechnology applications. We obtained highly wettable dextran coatings applied to flat silicon wafer surfaces through a two-step process: in the first step, the silicon is aminated by the deposition of a selfassembled monolayer of 3-aminopropyltriethoxysilane (APTES); in the second step, polydisperse and low dispersity dextrans with molecular weights ranging from 1 kDa to 100 kDa are covalently grafted along the backbone to the surface amino groups to achieve strong interfacial anchoring. The effect of dextran concentration on film thickness and contact angle is investigated. Atomic force microscopy (AFM) has been employed to characterize surface roughness and coverage of the dextrans as well as the APTES monolayers. The synthetic surfaces were also tested for gas bubble adhesion properties.