In vitro investigation of protein adsorption and platelet adhesion on inorganic biomaterial surfaces

The aim of this paper was to study the surface properties, protein adsorption and platelet adhesion behaviors of diamond-like carbon (DLC) and titanium (Ti) films. The surface energy and microstructures of these films were characterized by contact angle measurement and atomic force microscopy (AFM). A modified Coomassie brilliant blue (CBB) protein assay was used to study the amount of adsorbed proteins. Platelet adhesion was assessed by scanning electron microscopy (SEM). The AFM results show that the DLC film is smoother than Ti. Protein adsorption results from CBB protein assay show that the ratio of adsorbed albumin (Alb) to IgG (R_A/I) on DLC is larger than Ti, which coincide with the sequence of the ratio of interfacial tension between solid surface and Alb (γ_S,Alb) to interfacial tension between surface and IgG (γ_S,IgG) (γ_S,Alb/γ_S,IgG). The DLC film has a preferential adsorption for Alb. The results suggest that the ratio of γ_S,Alb/γ_S,IgG may indicate an Alb/IgG affinity ratio of materials. More platelets adhere on Ti film than on DLC, which may correspond to the surface roughness of materials. The conclusion is the blood compatibility of DLC seems to be better than Ti.