A comparative study of protein adsorption on titanium - Hook et al. Round robin - Colloids and Surfa

       The adsorption kinetics of three model proteins—human serumalbumin, fibrinogen and hemoglobin—has been measured and compared using three different experimentaltechniques: optical waveguide lightmode spectroscopy (OWLS), ellipsometry (ELM) and quartz crystal microbalance (QCM-D).The studies were complemented by also monitoring the corresponding antibody interactions with thepre-adsorbed protein layer. All measurements were performed with identically prepared titanium oxide coatedsubstrates. All three techniques are suitable to follow in-situ kinetics of protein–surface and protein–antibodyinteractions, and provide quantitative values of the adsorbed adlayer mass. The results have, however, different physicalcontents. The optical techniques OWLS and ELM provide in most cases consistent and comparable results, which can bestraightforwardly converted to adsorbed protein molar (‘dry’) mass. QCM-D, on the other hand, produces measured valuesthat are generally higher in terms of mass. This, in turn, provides valuable, complementary information in tworespects: (i) the mass calculated from the resonance frequency shift includes both protein mass and water that binds orhydrodynamically couples to the protein adlayer; and (ii) analysis of the energy dissipation in the adlayer and itsmagnitude in relation to the frequency shift (c.f. adsorbed mass) provides insight about the mechanical/structuralproperties such as viscoelasticity. © 2002 Elsevier Science B.V. All rights reserved.