Dr. Yamashita, Yuji
Presentation day
Tuesday 11:20 AM
TITLE
Self-assembling behaviour of tranexamic acid cetyl hydrochloride in aqueous solution
Abstract
Tranexamic acid cetyl hydrochloride (TXC), which is synthesized by chemically modifying
the tranexamic acid with the hydrophobic C16-chain, is utilized as an active ingredient in cosmetics. The
chemical structure results in the higher hydrophobicity than water-soluble tranexamic acid which help
percutaneous absorption through stratum corneum. Although TXC was designed for the sake of the
transdermal permeability to enhance bioavailability, we are interested in its structure as cationic amphiphile.
Therefore, we focused on the amphiphilic nature of TXC and the phase behaviour in its aqueous systems.
Binary mixtures at different compositions showed a variety of self-assembling structures. Increasing TXC
concentration induced phase transition from the micellar solution to the lamellar liquid crystal (Lα) via the
hexagonal liquid crystal. Comparing with the general cationic surfactant systems, the TXC system showed
highly organized orientation of LC, the higher Krafft temperature, and the lower critical micellar
concentration due to its strong inter-molecular interaction between cyclohexyl groups which is a rigid sixmembered
ring conformation in the molecule. SAXS, DSC, and POM measurements demonstrated the
specific molecular packing of TXC below and above the Krafft temperature. In our presentation, we will
introduce an interesting self-assembly structure by TXC with cyclohexyl hydrophobe in the center of the
molecule as a new generation amphiphile. In addition, the presence of CnOH allowed to expand interlayer
water domain of the lamellae to accommodate large amount of confined water, which will possibly develop
novel cosmetic formulations such as emulsification.
CV
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2000 Bachelor's Degree, Yokohama National University, Faculty of Engineering, Division of Materials Science and Chemical Engineering
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2002 Master's Degree, Yokohama National University, Graduate School of Environment and Information Sciences
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2005 Doctoral Degree, Bayreuth University
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2005 - 2009 CHISSO Corporation, 1st Research Center
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2009 - 2011 Post Doctoral Researcher, St. Marianna University Graduate School of Medicine, Department of Frontier Medicine
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2011 - Current Assistant Professor, Chiba Institute of Science
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2011-2014 Assistant Professor, Chiba Institute of Science
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2014-Current Junior Associated Professor, Chiba Institute of Science
Literatures
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Y. Yamashita, H. Hoffmann, H. Maeda, L. Li, M. Ballauff,"Aggregation and Phase Behavior of a Double-Chain Surfactant, N-Dodecyl-N-octyl-N-methylamine Oxide, as a Function of the Protonation Degree", Langmuir, 23, 1073-1080, 2007
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Y. Yamashita, H. Maeda, H. Hoffmann,"Counterion Specificity in The Phase Behavior of Tetradecyl-dimethylamine Oxide at Different Degrees of Protonation", J. Colloid and Interface Sci., 299, 388-395, 2006
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Y. Yamashita, H. Kunieda, E. Oshimura, K. Sakamoto, "Formation of Intermediate Micellar Phase between Hexagonal and Discontinuous Cubic Liquid Crystals in Brine/N-Acylamino Acid Surfactant/N-Acylamino Acid Oil System", J. Colloid and Interface Sci., 312, 172-178, 2006
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