Adsorption of proteins on an AISI 316 stainless-steel surface in natural seawater

The surface of a metal immersed in solutions containing organic and inorganic molecules is modified by an adsorbed layer that influences the subsequent biofilm formation. Little is known about the first steps of surface modifications in the complex medium of seawater. The 'BASIS' group has characterized the conditioning film formed on a stainless-steel surface immersed in natural seawater. The chemical composition, morphology and growth mode of this film have been determined using complementary surface analytical techniques: x-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRAS), atomic force microscopy (AFM), surface free energy measurements and time-of-flight secondary ion mass spectrometry (ToF-SIMS), The XPS and ToF-SIMS data show that the primary film is mainly composed of proteins in the early stages of immersion. The SIMS, XPS, surface free energy and AFM data indicate that the adsorbed protein layer is discontinuous, leaving bare oxide areas. Our results and interpretations are supported by similar experiments in artificial seawater containing controlled amounts of proteins. Copyright (C) 2000 John Wiley & Sons, Ltd.