Protein-surface interactions studied by infrared spectroscopy

Interactions of human fibrinogen and human serum albumin in aqueous buffers with germanium, polyethylene, and carbon planar surfaces were studied by IR internal reflection spectroscopy. The method is shown to be able to monitor continuously and in situ adsorption rates with high time-resolution (0.5 s), to produce data concerning reversibility of interactions, and to detect surface induced changes of proteins. Albumin and fibrinogen interact with the strongly hydrophobic surfaces irreversibly and fibrinogen interacts irreversibly even during the first 15 s of adsorption. Differences between spectra of the proteins adsorbed and in solution were detected and interpreted as surface induced changes. Anomalously high and partly reversible adsorption of HFb during certain experiments is connected with its denaturation. No effect of thrombin and plasmin on adsorbed HFb was indicated from its spectra.