Analytical Sciences

An Amperometric D-Amino Acid Biosensor Prepared with a Thermostable D-Proline Dehydrogenase and a Carbon Nanotube-Ionic Liquid Gel

Yuji TANI,*¹ Yukiko ITOYAMA,*¹ Kenichi NISHI,*¹ Chikahiro WADA,*¹ Yoshio SHODA,*¹ Takenori SATOMURA,*² Haruhiko SAKURABA,*³ Toshihisa OHSHIMA,*⁴ Yukako HAYASHI,*¹ Tomoki YABUTANI,*¹ and Junko MOTONAKA*¹

*1 Department of Chemical Science and Technology, Institute of Science and Tecnhology, The University of Tokushima, 2-1 Minami-josanjima, Tokushima 770-8506, Japan
*2 Department of Materials Science, Yonago National College of Technology, 4448 Hikona, Yonago, Tottori 683-8506, Japan
*3 Department of Applied Biological Science, Faculty of Agriculture & Graduate School of Agriculture, Kagawa University, 2393 Ikenobe, Miki, Kita, Kagawa 761-0795, Japan
*4 Microbial Genetics Division, Institute of Genetic Resources, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi, Fukuoka 812-8581, Japan

Carbon nanotube (CNT) gel, which is composed of a mixture of single-wall CNT, an ionic liquid, and a thermostable D-proline dehydrogenase (D-Pro DH) immobilized electrode was utilized for the determination of D-amino acids (DAAs) in food samples. When a critical comparison with CNT, Ketjen Black (KB), and carbon powder (CP) was also carried out, the CNT/D-Pro DH immobilized electrode showed the highest sensitivity and the lowest detection limit of D-proline. In addition, the CNT/D-Pro DH immobilized electrode was applied to detection of DAAs in rice wine and vinegar samples. The concentrations of DAAs in rice wine and vinegar samples were 0.0210 ± 0.0001 and 0.55 ± 0.05 mmol L⁻¹, respectively.

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