Abstract
Poly (2-methoxyethylacrylate) (PMEA) surface shows good blood compatibility with respect to the coagulation, complement, and platelet systems when compared with other polymer surfaces. To clarify the reasons for this good compatibility, the amount of the plasma protein adsorbed onto PMEA and its secondary structure were investigated. Poly (2-hydroxyethylmethacrylate) (PHEMA) and polyacrylate analogs were used as references. The amount of protein adsorbed onto PMEA was very small, and close to that adsorbed onto PHEMA. Circular dichroism (CD) spectroscopy revealed that the conformations of the proteins adsorbed onto PHEMA changed considerably, while those of the proteins adsorbed onto PMEA differed only slightly from the native one. Based on the quartz crystal microbalance (QCM) measurement, we estimated the binding constant and association and dissociation rate constants of the proteins adsorbed onto the polymer surfaces. These results suggested that the excellent blood compatibility of PMEA is closely related to the low denaturation and the high dissociation rate constant of the proteins adsorbed onto PMEA. In addition, the structure of water in the hydrated PMEA was investigated using differential scanning calorimetry (DSC). Cold crystallization of water in the heating process was clearly observed at -42°C. This cold crystallization is interpreted as the phase transition from the amorphous ice to the crystal ice that belongs to the freeze-bound water in PMEA. We believe that this feature of the water structure is related to blood compatibility.
