Presentation Information
[9a-E301-4]Direct Visualization of Hydration Structures on Poly(2-methoxyethyl acrylate) and Poly(n-butyl methacrylate) by Frequency Modulation AFM
〇Yilin Wang1, Takuma Tsukishima1, Akihiro Hiraki2, Yihua Liu2, Takao Anzai2, Yoshihiko Abe2, Hirofumi Yamada1, Kei Kobayashi1 (1.Kyoto Univ., 2.Terumo Corp.)
Keywords:
frequency modulation atomic force microscopy,hydration structure,intermediate water
Interfacial hydration governs the biological response of polymeric biomaterials, and the outstanding blood compatibility of poly(2-methoxyethyl acrylate) (PMEA) is widely attributed to highly mobile “intermediate water” that suppresses irreversible protein adsorption.1 However, local layering and mechanical response of such hydration structures have never been directly observed. Here, we use ultralow-noise frequency modulation atomic force microscopy (FM-AFM), which resolves individual hydration layers at solid–liquid interfaces,2 to compare the hydration on blood-compatible PMEA and protein-adsorbing poly(n-butyl methacrylate) (PBMA) in phosphate-buffered saline (PBS). Sub-nanometer frequency shift mapping combined with nanomechanical analysis reveals two distinct water architectures. As shown in Figure 1, on PBMA, water forms a rigid, multilayered structure with a periodicity of approximately 0.30 nm, whereas PMEA shows no detectable layering. These results provide direct mechanical evidence for a highly mobile, dynamically fluctuating “intermediate water” layer at the PMEA interface that acts as a dynamic physical barrier against protein adsorption. Knowledge of nanoscale hydration structures at polymer/water interfaces obtained by FM-AFM is important for designing blood-compatible biomaterials and improving their biological performance.