1. a School of Materials Science, Japan Advanced Institute of Science and Technology, 15 Asahidai, Tatsuno-kuchi, Ishikawa 923-12, Japan
2. b Institute of Biomedical Engineering, Tokyo Women's Medical College, 8-1 Kawada-cho, Shinjuku, Tokyo 162, Japan
3. c Institute of Biomedical Engineering, Tokyo Women's Medical College, 8-1 Kawada-cho, Shinjuku, Tokyo 162, Japan
4. d Institute of Biomedical Engineering, Tokyo Women's Medical College, 8-1 Kawada-cho, Shinjuku, Tokyo 162, Japan
5. e Department of Applied Chemistry, Keio University, 3-14-1Hiyoshi, Kohoku, Yokohama 223, Japan
6. f Department of Applied Chemistry, Keio University, 3-14-1Hiyoshi, Kohoku, Yokohama 223, Japan
7. g Department of Applied Chemistry, Keio University, 3-14-1Hiyoshi, Kohoku, Yokohama 223, Japan
8. h Department of Applied Chemistry, Keio University, 3-14-1Hiyoshi, Kohoku, Yokohama 223, Japan