title: Selective encapsulation of cesium ions using the cyclic peptide moiety of surfactin: Highly efficient removal based on an aqueous giant micellar system.
abstract: Cyclic peptide of surfactin (SF) is one of the promising environment-friendly biosurfactants abundantly produced by microorganisms such as Bacillus subtilis. SF is also known to act as an ionophore, wherein alkali metal ions can be trapped in the cyclic peptide. Especially, SF is expected to show high affinity for Cs(+) because of the distinctive cavity size and coordination number. In this study, we reported the specific interaction between SF and Cs(+) and succeeded in the highly efficient removal of Cs(+) from water using giant SF micelles as a natural sorbent. The specific interaction between SF and Cs(+) to form their inclusion complex was revealed by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy. We found that SF micelles selectively encapsulate Cs(+), which was suggested by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). A highly effective separation of Cs(+) immobilized on the surface of the SF micelles was also achieved through facile centrifugal ultrafiltration in 91% even in coexisting with other alkali metal ions such as Na(+) and K(+). Thus, the use of the giant micellar system of SF with its high Cs(+) affinity and distinctive assembling properties would be a new approach for the treatment of contaminated soil and water.
authors.affiliation: Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Taira
authors.affiliation: New Business Development Division, Kaneka Corporation, 2-3-18, Nakanoshima, Kita-ku, Osaka 530-8288, Japan.
authors.forename: Satohiro
authors.initials: S
authors.lastname: Yanagisawa
authors.affiliation: New Business Development Division, Kaneka Corporation, 2-3-18, Nakanoshima, Kita-ku, Osaka 530-8288, Japan.
authors.forename: Takuto
authors.initials: T
authors.lastname: Nagano
authors.affiliation: National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
authors.forename: Yanbei
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (AIST), Central 3, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kuroiwa
authors.affiliation: Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Nagatoshi
authors.initials: N
authors.lastname: Koumura
authors.affiliation: Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Dai
authors.initials: D
authors.lastname: Kitamoto
authors.affiliation: Research Institute for Chemical Process Technology, National Institute of Advanced Industrial Science and Technology (AIST), Central 5-2, 1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan. Electronic address: t-imura@aist.go.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Imura
mesh_terms: D002586:Cesium / Q000302:isolation & purification*; D055666:Lipopeptides / Q000737:chemistry*; D010456:Peptides, Cyclic / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D055666:Lipopeptides; D010456:Peptides, Cyclic; D002586:Cesium; C009365:surfactin peptide
keywords: Biosurfactant; Cesium; Cyclic peptide; Micelle; Surfactin