a *Corresponding author. Tel: +81-26-269-5740. E-mail: Tsuruoka.saitama@gmail.com (Shuji Tsuruoka) b *Co-Corresponding author. Tel: +81-3-5734-3640, E-mail: matsumoto.h.ac.@m.titech.ac.jp (Hidotoshi Matsumoto) Differentiation of Chemical Reaction Activity of Various Carbon Nanotubes Using Redox Potential: Classification by Physical and Chemical Structures Shuji Tsuruoka a* , Hidetoshi Matsumoto b* , Vincent Castranova c , Dale W. Porter d , Takashi Yanagisawa e , Naoto Saito f , Shinsuke Kobayashi f , and Morinobu Endo g a Aquatic Innovation Center, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 Japan b Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, Japan c West Virginia University, Morgantown, WV, USA. d Pathology & Physiology Research Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Rd. (M/S2015) Morganton, WV, USA. e GSI Creos Corporation, 1-12, Minami-Watarida-cho, Kawasaki, Kanagawa, 210-0855, Japan f Department of Applied Physical Therapy, Shinshu University, School of Health Sciences, 3- 1-1 Asahi, Matsumoto, Nagano, Japan g Institute of Carbon Science and Technology, Shinshu University, Nagano 380-8553 Japan © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/