Hierarchical analyses of manifestation mechanism of biocompatibility

Using sum frequency generation (SFG) spectroscopy, it was found that water molecules in the vicinity of zwitterionic and charge-neutralized polymer materials are not largely oriented in comparison with those in the vicinity of lopsidedly charged polymer materials. Taking account of excellent anti-coagulant and biocompatible properties of the zwitterionic and charge-neutralized polymer materials, the absence or drastic reduction of the orientation of vicinal water molecules is suggested to be very essential for the bio-inertness of polymer materials. Furthermore, using the temperature-variable infrared spectroscopy and molecular dynamics, it was found that the so-called recrystallization phenomena observed in the water-saturated anti-coagulant polymer materials such as poly(2-methoxyethyl acrylate) (PMEA) are not dominated by the reorientation but the diffusion process of water molecules within the polymer materials.