Biomimetic Dextran Coatings On Silicon Wafers: Thin Film Properties And Wetting

Abstract

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. ABSTRACTThere 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.

A quantitative and selective chromatography method for determining coverages of multiple proteins on surfaces

“…The CHAPS/HPLC method was tested using bare silicon as a control and dextran-grafted silicon surfaces synthesized and characterized in our laboratories [28][29][30]. The dextran grafting chemistry was extended to double-sided surfaces to provide a sufficiently large homogeneous sample that would nominally adsorb microgram quantities of proteins (i.e., sufficient for detection by UV absorption).…”

“…The details regarding the preparation and characterization of these surfaces can be found in previous publications [28][29][30]. The dextranized [13] surface for this experiment was obtained by oxidizing dextran for 0.5 h prior to grafting on amino-functionalized silicon [30].…”

“…Briefly, our dextran grafting procedure was developed on single side polished silicon wafers cut into squares of approximately 1 cm 2 . However, this surface area is too small to adsorb enough protein to be detected by HPLC which has a sensitivity determined by the efficiency of the UV detector, namely about 1 g. To overcome this issue, we therefore adapted our dextran grafting procedure [28][29][30] to double side polished silicon wafers which present a surface area of ∼40 cm 2 for protein adsorption.…”

Competitive protein adsorption on polysaccharide and hyaluronate modified surfaces

“…We prepared dextranized silicon wafers using the experimental method detailed in previous publications (Miksa et al 2004; Miksa et al 2006; Ombelli et al 2002; Ombelli et al 2003; Ombelli et al 2005). The dextranized surface for this experiment was obtained by oxidizing dextran for either 0.5 or 4 h prior to grafting on amino-functionalized silicon, with full detail of the method having been previously reported (Miksa et al 2006).…”

“…In previous studies we demonstrated our ability to prepare dextran coatings in which we controlled thickness, wettability and roughness by varying molecular weight, polydispersity (Ombelli et al 2002; Ombelli et al 2003) and degree of oxidation (Miksa et al 2004; Miksa et al 2006). We now extend that work to evaluate competitive adsorption of bovine serum albumin (BSA) and bovine fibrinogen (Fg) onto dextranized as well as introduce competitive adsorption on sodium hyaluronate (HA) coatings.…”