Which ismore effective for protein adsorption: Surface roughness, surface wettability or swelling? Case study of polyurethane films prepared from castor oil and poly(ethylene glycol)

In order to investigate the effects of surface roughness, surface wettability and swelling on protein adsorption, polyurethane films were prepared from castor oil (CO) and poly(ethylene glycol)-3000 (PEG) using one-shot bulk polymerization. Hexamethylene diisocyanate and 1,4-butanediol were used as isocyanate and chain extender, respectively. The hydrophilicity of the polyurethane films was adjusted by varying the ratio of CO to PEG. The surface of the polyurethane films was treated using plasma polymerization in the presence of acrylic acid vapour. Therefore, the polyurethane films could be obtained with the same hydrophilicity but with different roughness. The hydrophilicity of untreated and treated polymer films was examined using contact angle measurements. The surface topology of the polymer films was investigated using scanning electron microscopy and atomic force microscopy. Adsorption of bovine serum albumin and bovine serum fibrinogen on treated and untreated polymer films was determined and the performance of the films was compared. After evaluation of all results it is found that surface roughness and swelling are as important as hydrophilicity for protein adsorption in the case of CO/PEG-based polyurethanes.