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Effects of Thermoresponsive Coacervation on the Hydrolytic Degradation of Amphipathic Poly(γ-glutamate)s

Authors

  • Taiki Shimokuri,

    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka Suita, 565-0871, Japan
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  • Tatsuo Kaneko,

    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka Suita, 565-0871, Japan
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  • Mitsuru Akashi

    Corresponding author
    1. Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka Suita, 565-0871, Japan
    2. Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan
    • Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Tokyo, Japan.
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Abstract

Summary: Hydrolytic properties of thermoresponsive biopolymers with amphiphilic structures, γ-PGA-P, were investigated. Hydrolysis was monitored in terms of molecular weight changes using GPC and spectroscopic measurements. The hydrolytic degradation of γ-PGA-P was controlled by a change in the degree of propyl group conversion, reaction temperature, and/or reaction pH. The degradation was classified as the rapid elimination of propyl side chains and the moderate cleavage of peptide linkages in the backbone. Furthermore, hydrophobic environments established by the thermoresponsive coacervation of γ-PGA-P60 solutions inhibited hydrolytic degradation reactions. Inversely, hydrolytic degradations increased coacervation temperatures. Kinetic studies of hydrolytic reactions suggest that the degradation rate of γ-PGA-P60 solutions can be controlled by their thermoresponsivity. The hydrolysis reported here represents the first degradation rate controlled by thermoresponsive coacervation.

original image

A schematic illustration of the hydrolytic mechanism of γ-PGA-P60.

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