An article including a surface configured to contact a protein, the surface comprising a polymer composition comprising: - component (a): from 50 wt.% to 98.5 wt.% of a poly(ether sulfone) ("PES") polymer; - component (b): - from 1 wt.% to 40 wt.% of a polysulfone ("PSU") polymer or - from 1 wt.% to 40 wt.% of a poly(phenyl ether sulfone) ("PPSU") polymer or - from 1 wt.% to 40 wt.% of a mixture of and; - from 1 wt.% to 40 wt.% of at least one clay mineral filler wherein all the wt.% are relative to the total weight of the polymer composition and with the proviso that if the polymer composition comprises from 1 wt.% to 7 wt.%, preferably from 1 wt.% to 5 wt.% of PPSU polymer, the clay mineral filler is present at at least 7 wt.%, preferably at least 10 wt.% wherein the PES polymer comprises at least 50 mol.% recurring unit (R PES) of formula: wherein: - each R i, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium, and - each i, equal to or different from each other, is an integer ranging from 0 to 4, preferably wherein each i = 0, wherein the PSU polymer is of formula: wherein: - each R k, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium; - R' and R", equal to or different from each other, is selected from a hydrogen, a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium; and - each k, equal to or different from each other, is an integer ranging from 0 to 4, preferably wherein each k = 0 and/or wherein R' and R" are a methyl group, wherein the PPSU polymer is of formula: wherein: - each R l, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium, and - each I, equal to or different from each other, is an integer ranging from 0 to 4, preferably wherein each I = 0 and/or wherein the mineral filler comprises kaolin or mica. - component (a): from 50 wt.% to 98.5 wt.% of a poly(ether sulfone) ("PES") polymer; - component (b): - from 1 wt.% to 40 wt.% of a polysulfone ("PSU") polymer or - from 1 wt.% to 40 wt.% of a poly(phenyl ether sulfone) ("PPSU") polymer or - from 1 wt.% to 40 wt.% of a mixture of and; - from 1 wt.% to 40 wt.% of a polysulfone ("PSU") polymer or - from 1 wt.% to 40 wt.% of a poly(phenyl ether sulfone) ("PPSU") polymer or - from 1 wt.% to 40 wt.% of a mixture of and; - from 1 wt.% to 40 wt.% of at least one clay mineral filler - each R i, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium, and - each i, equal to or different from each other, is an integer ranging from 0 to 4, preferably wherein each i = 0, - each R k, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium; - R' and R", equal to or different from each other, is selected from a hydrogen, a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium; and - each k, equal to or different from each other, is an integer ranging from 0 to 4, preferably wherein each k = 0 and/or wherein R' and R" are a methyl group, - each R l, equal to or different from each other, is selected from a halogen, an alkyl, an alkenyl, an alkynyl, an aryl, an ether, a thioether, a carboxylic acid, an ester, an amide, an imide, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, an alkali or alkaline earth metal phosphonate, an alkyl phosphonate, an amine, and a quaternary ammonium, and - each I, equal to or different from each other, is an integer ranging from 0 to 4, preferably wherein each I = 0 and/or wherein the mineral filler comprises kaolin or mica.