The adsorption behavior of human fibrinogen with different concentrations and pH variation on gold surfaces has been investigated using quartz crystal microbalance with dissipation(QCM-D) monitoring at 25 degrees C. Two different protein concentrations have been used, one close to in vivo concentration(1 mg/ml) and one significantly lower(0.01 mg/ml). To further characterize the influence of pH variation on the adsorbed Fibrinogen layer, the subsequent binding of monoclonal antibody of fibrinogen is studied by enzyme-linked immunosorbent assay(ELISA). We find that the fibrinogen shows different adsorption behavior at different concentration and pH, and the conformation can be influenced by pH variation. From this we conclude that the protein adsorption behavior on a surface depends strongly on the protein concentration and pH variation in solution, and the binding of antibody is a useful method to detect the influence of pH on absorbates conformational change. (C) 2008 Elsevier B.V. All rights reserved.