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

The surface of a metal immersed in solutions containing organic and inorgan ic molecules is modified by an adsorbed layer that influences the subsequen t biofilm formation. Little is known about the first steps of surface modif ications in the complex medium of seawater. The 'BASIS' group has character ized the conditioning film formed on a stainless-steel surface immersed in natural seawater. The chemical composition, morphology and growth mode of t his film have been determined using complementary surface analytical techni ques: x-ray photoelectron spectroscopy (XPS), infrared reflection absorptio n spectroscopy (IRAS), atomic force microscopy (AFM), surface free energy m easurements 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 ener gy 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.