Reduction of protein adsorption on silica and polysulfone surfaces coated with complex coacervate core micelles with poly(vinyl alcohol) as a neutral brush forming block

We have studied the formation and stability of complex coacervate core micelles (C3Ms) in solution, and the influence of C3M coatings on the adsorption of the proteins β-lactoglobulin (β-lac), bovine serum albumin (BSA), and lysozyme (Lsz) on silica and polysulfone surfaces. The C3Ms consist of a block copolymer PAA50-65-b-PVA445 (poly(acrylic acid)-b-poly(vinyl alcohol)), with a neutral PVA block, and the positively charged homopolymers: P2MVPI (poly(N-methyl 2-vinyl pyridinium iodide), or PAH·HCl (poly(allylamine hydrochloride)). In solution at pH 7 these micelles disintegrate if the salt concentration exceeds 100 mM NaCl. Adsorption of C3Ms and proteins was studied by fixed angle optical reflectometry at salt concentrations ranging from 1 to 50 mM NaCl. C3M consisting of PAH·HCl strongly suppresses protein adsorption on silica, also at low salt concentration. However, at high salt concentrations it enhances adsorption of BSA on hydrophobic polysulfone, probably due to the formation of complexes between BSA and PAH·HCl. Much smaller reduction of protein adsorption on silica and polysulfone was obtained by C3Ms consisting of P2MVPI.. In this case the effectiveness of the coating strongly depends on the type of protein. On polysulfone at 50 mM NaCl we have observed only reduction of Lsz adsorption whereas adsorption of the negatively charged proteins is enhanced rather than reduced by the coating. We relate the results obtained for C3M with P2MVPI to the low density of the PVA chains on the surfaces, partial segregation of polymer chains within coacervate layer, and penetration of the adsorbed layer by the proteins.