Spectroscopic ellipsometry was used to characterize the optical properties of thin (<5 nm) films of nanostructured titanium dioxide (TiO(2)). These films were then used to investigate the dynamic adsorption of bovine serum albumin (BSA, a model protein), as a function of protein concentration, pH, and ionic strength. Experimental results were analyzed by an optical model and revealed that hydrophobic interactions were the main driving force behind the adsorption process, resulting in up to 3.5 mg/m(2) of albumin adsorbed to nanostructured TiO(2). The measured thickness of the adsorbed BSA layer (less than 4 nm) supports the possibility that spreading of the protein molecules on the material surface occurred. Conformational changes of adsorbed proteins are important because they may subsequently lead to either accessibility or inaccessibility of bioactive sites which are ligands for cell interaction and function relevant to physiology and pathology.