1. Contribution from the Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Department of Materials and Life Sciences, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita City, Osaka 565-0871, and Products Development Department 2, Micro-Imaging Systems Division, OLYMPUS CORPORATION, 2951 Ishikawa-cho, Hachioji-shi, Tokyo 192-8507, Japan