Protein adsorption on stainless steel in aqueous solution: an EIS, XPS, andIRRAS study

摘要

The adsorption of Bovine Serum Albumin (BSA), and its influence on the electrochemicalrnbehaviour in deaerated 0.05M H2SO4 solution of a ferritic stainless steel, Fe-17Cr, wasrnstudied by electrochemical methods (time dependence of the corrosion potential Ecor,rnpolarization curves, EIS) and surface analysis techniques (PM-IRRAS, XPS). Thernelectrochemical measurements show a corrosion inhibition by the BSA at Ecor. The chargerntransfer resistance decreases and hence the corrosion current of the alloy increases withrnimmersion time at Ecor, but this phenomenon is much less marked in the presence of BSA.rnThe LF response of the impedance diagrams plotted at Ecor and its evolution with immersionrntime is modified by the presence of the BSA, which suggests that the protein is directly orrnindirectly involved in the electrochemical processes at Ecor. Impedance measurementsrnperformed after passivation of the alloy at 0 V vs. SSE show that the presence of protein hasrnno effect on the electrochemical behaviour of the passivated alloy surface. Surface analysis ofrnthe stainless steel samples by PM-IRRAS and XPS shows that the BSA is present on thernsurface at both Ecor and 0 V. From the detailed analysis of the C 1s XPS region, it can bernconcluded that the BSA molecules adsorbed on the surface at both potentials are chemicallyrnintact. The amount of adsorbed BSA is quite similar at Ecor and 0 V. All these resultsrndemonstrate that the adsorption of BSA takes place on the Fe-17Cr surface both at therncorrosion potential and in the passive region, and the BSA has a corrosion inhibition effectrnwhen the surface is not fully passivated.