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LCST/UCST-type thermosensitive properties of carboxy-terminal PAMAM dendrimers modified with different numbers of phenylalanine residues

Polymer Journal volume 57, pages 137–142 (2025)Cite this article

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Abstract

Stimuli-sensitive polymers are useful smart materials. Dendrimers are synthetic polymers with well-defined structures, and various functional dendrimers have been produced by modifying compounds at their termini. We previously reported that polyamidoamine (PAMAM) dendrimers modified with cis-1,2-cyclohexane dicarboxylic acid (CHex) and phenylalanine (Phe), named PAMAM-CHex-Phe, exhibit upper critical solution temperature (UCST)-type thermosensitivity at acidic pH. In this study, we synthesized PAMAM dendrimers with CHex and various numbers of bound Phe residues and examined their pH and temperature sensitivities. Interestingly, PAMAM-CHex-Phe, with fewer than 32 Phe residues, showed lower critical solution temperature (LCST)-type thermosensitivity at pH 5 but not UCST-type thermosensitivity. PAMAM-CHex-Phe40 and PAMAM-CHex-Phe48 exhibited both LCST- and UCST-type thermosensitivity at pH values of 5 and 6, respectively. Fully Phe-modified PAMAM-CHex-Phe (PAMAM-CHex-Phe64) showed UCST-type but not LCST-type thermosensitivity. pH titration experiments suggested that the protonation behaviors of these dendrimers were different, likely resulting in different phase transitions. Therefore, the phase transition temperature and behavior could be regulated by varying the number of bound Phe residues in the PAMAM-CHex-Phe dendrimers and the solution pH.

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Acknowledgements

This work was supported by JSPS KAKENHI Grant numbers JP20H05232, JP22H04556 and JP19H05714 (Grant-in-Aid for Scientific Research on Innovative Areas: Aquatic Functional Materials). This work was also supported by the Izumi Science and Technology Foundation.

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  1. Chie Kojima

    Present address: Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8503, Japan

Authors and Affiliations

  1. Department of Applied Chemistry, Graduate School of Engineering, Osaka Metropolitan University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka, 599-8531, Japan

    Hiroya Shiba, Akikazu Matsumoto & Chie Kojima

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  1. Hiroya Shiba
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  2. Akikazu Matsumoto
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Correspondence to Chie Kojima.

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HS is an employee of Kao Co., Ltd. The other authors declare no competing interests.

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41428_2024_963_MOESM1_ESM.docx

LCST/UCST-Type Thermosensitive Properties of Carboxy-Terminal PAMAM Dendrimers Modified with Different Numbers of Phenylalanine Residues

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Shiba, H., Matsumoto, A. & Kojima, C. LCST/UCST-type thermosensitive properties of carboxy-terminal PAMAM dendrimers modified with different numbers of phenylalanine residues. Polym J 57, 137–142 (2025). https://doi.org/10.1038/s41428-024-00963-0

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