Modification of food contacting surfaces by plasma polymerization technique. Part II: Static and dynamic adsorption behavior of a model protein “bovine serum albumin” on stainless steel surface

The static and dynamic adsorption behaviors of a model protein “Bovine Serum Albumin” on plain (SS 316) and 2-hydroxethylmethacrylate (HEMA) or polyethyleneglycolmethacrylate (PEGMA) plasma polymerization (PlzP) modified stainless steel surfaces were studied. For equilibrium adsorption behavior, Freundlich model was attempted and model parameters for Freundlich (KF and n) were obtained. The values of the KF and n were 24.4, 0.88; 14.9, 0.83 and 19.7, 0.85 for, SS 316, PlzP(HEMA) and PlzP(PEGMA) surfaces, respectively. The results of “static” equilibrium adsorption studies showed that, a monolayer of the protein molecules formed next to the solid surface. The dynamic adsorption process reached to the plateau value around 160 min for SS 316, 150 min for PlzP(PEGMA) and 75 min for PlzP(HEMA) surfaces. The total amount of BSA adsorbed on the SS 316, PlzP(HEMA) and PlzP(PEGMA) surfaces at the plateau were calculated as, 4.35, 2.77 and 0.38 mg, respectively. A parameter to define the dynamic behavior of the adsorption so called “Initial adsorption rate” were introduced and calculated for of BSA adsorption on the SS 316, PlzP(HEMA) and PlzP(PEGMA) surfaces as, 33 × 10−7, 3 × 10−7 and 10 × 10−7 g/min cm2, respectively. These dynamic results are in a very good agreement with the results obtained in static adsorption tests.