Competitive protein adsorption on biomaterial surface studied with reflectometric interference spectroscopy

Reflectometry interference spectroscopy (RIfS) is known as a highly sensitive and robust technique for direct, label-free detection of the interaction of biomacromolecules in real time and in situ. The aim of the present study was to investigate the competitive protein adsorption on the surface of fluorocarbon end-capped poly(carbonate) urethane (PCUF) and polystyrene (PS) based on the RIfS method. The surface energy and microstructures of PCUF and PS were characterized by contact angle measurement and atomic force microscopy. Interfacial energies between these surfaces and the proteins were then calculated. The protein adsorption experiments were carried out with both single solution and ternary solutions composed of albumin, fibrinogen and immunoglobulin-G (IgG). The results of surface characterization showed that PCUF was more hydrophilic than PS with a smaller surface energy, and micro-phases separation of PCUF was observed. RIfS analysis results revealed that more albumins, less fibrinogen and IgG were detected on the PCUF surface compared with PS after simplex and competitive protein adsorption, which indicated that PCUF had a preferential adsorption for albumin. The special morphology, smaller surface energy and calculated interfacial energies between PCUF and proteins may be responsible for the better blood compatibility of PCUF compared to PS. The results suggest that RIfS could serve as a novel, effective method for studying the competitive protein adsorption on biomaterial surfaces.