1. Department of Biomaterials, Faculty of Medicine, Dentistry and Pharmaceutical Sciences Okayama University 2‐5‐1 Shikata‐cho, Kita‐ku Okayama City Okayama 700‐8558 Japan
2. Division of Hepato‐Biliary‐Pancreatic Surgery, Department of Surgery Kobe University Graduate School of Medicine 7‐5‐2 Kusunoki‐Cho, Chuou‐Ku Kobe City Hyogo 650‐0017 Japan
3. Soft Materials Chemistry, Institute of Material Chemistry and Engineering, Department of Applied Chemistry, Graduate School of Engineering Kyushu University 744 Motooka, Nishi‐ku Fukuoka City Fukuoka 819‐0395 Japan
4. Division of Materials and Manufacturing Science, Graduate School of Engineering Osaka University 2‐1 Yamadaoka Suita City Osaka 565‐0871 Japan