1. Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8246, Japan
2. Biomacromolecules Research Team, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
3. Support Unit for Bio-Material Analysis, Research Resources Division, RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
4. Department of Electrical Engineering and Information Systems, The University of Tokyo, Tokyo 113-8656, Japan