Fibrinogen adsorption behavior on the blood-compatible polymer, poly(2-methoxyethyl acrylate) (PMEA), non-blood-compatible polymer, poly(n-butyl acrylate) (PBA), and random copolymers of both were examined. Adsorption and denaturation of fibrinogen on the polymers increased as the ratio of PBA increased. The incremental change corresponded to the amount of intermediate water included in the hydrated polymers. The composition of PBA altered the features of the phase-separated structures observed on the polymer/phosphate-buffered saline interfaces. Microscopically, the denaturation of fibrinogen was observed as the formation of fibrous networks on the interfaces by atomic force microscopy. Fibrinogen adsorption and denaturation were enhanced on the water-rich domains in the phase-separated structures on the non-blood-compatible polymers. This suggested that the excellent blood compatibility of PMEA is caused by the constrained adsorption and denaturation of fibrinogen in water-rich domains, possibly due to the high content of intermediate water in this region. This work provides essential scientific foundations for the design and fabrication of highly functional biomaterials.
Keywords: Random copolymer; fibrinogen; intermediate water; phase separation.