Interaction between heparin and fibronectin: Using quartz crystal microbalance with dissipation, immunochemistry and isothermal titration calorimetry

The adsorption behavior of heparin and fibronectin was studied by quartz crystal microbalance with dissipation (QCM-D), and the interaction between heparin and fibronectin was evaluated using immunochemistry and isothermal titration calorimetry (ITC) measurement. The results showed that there was competitive adsorption between heparin and fibronectin, and the preadsorption of fibronectin could prevent subsequent heparin adsorption to some extent, and the adsorbed Hep/Fn complex on the surface was in a rigid form. The bioactivity of heparin and fibronectin could be affected by the bulk concentration of each, and both heparin and fibronectin in Hep/Fn complex formed under pH 4 condition displayed larger bioactivity than that formed under pH 7 condition. Moreover, the fibronectin showed more exposed cell-binding sites at the pH value lower than physiological condition. The results of ITC further suggested that the interaction between heparin and fibronectin under pH 4 was stronger than under pH 7, and the complex was also more stable. The study brings forth the detailed interaction between heparin and fibronectin, which will be helpful for better understanding the interaction mechanism of the two biomolecules. The results may be potentially useful for the development of new generation of cardiovascular biomaterials.