ONLINE DETECTION OF NONSPECIFIC PROTEIN ADSORPTION AT ARTIFICIAL SURFACES

A detailed understanding of the interaction of proteins with artificia l surfaces is essential for many applications in medicine and biochemi stry. The affinity of surfaces toward proteins may, for instance, remo ve pharmacological proteins from media or control the adherence of pat hogenic bacteria to protheses, Only a few analytical techniques now ex ist that can be used to study the binding process in real time, using unlabeled proteins, By investigating the adsorption kinetics of fibrin ogen at differently terminated self-assembled monolayers (SAMs) of alk anethiols on thin gold films, it is demonstrated that acoustic plate-m ode sensors are a promising analytical tool for studying the adsorptio n of proteins, In agreement with previous studies for fibrinogen, it i s shown in situ that hexa(ethylene glycol)-terminated SAMs (HS(CH2)(11 )(OCH2CH2)(6)OH) exhibit very low protein adsorption and that methyl-t erminated SAMs (HS(CH2)(11)CH3) tend to adsorb large amounts of protei n nonspecifically. The observed adsorption kinetics deviate from class ical Langmuir behavior; these kinetics are compatible with a mechanism that involves an unfolding of fibrinogen after adsorption, Film quali ty is controlled by IR, XPS, and contact angle measurements.