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Hydrothermal crosslinking of poly(fluorenylamine) with styryl side chains to produce insoluble fluorescent microparticles


Fluorescent microbeads are emerging as optical probes for biological applications. However, insoluble crosslinked microbeads are difficult to synthesize. The existing methodology, in which polymerization occurs within dispersed micelles, is only applicable to a limited number of polymeric compounds. Herein, we report the hydrothermal synthesis of insoluble fluorescent microbeads. The newly designed and synthesized fluorenylamine-based polymers contained two styryl groups and self-assembled into spherical microparticles upon emulsification. In contrast to microparticles heated under atmospheric conditions, the microparticles became insoluble upon hydrothermal treatment and maintained their spherical morphology. Microparticles that contained a mixture of the thermosetting polymer with polystyrene resulted in an enhanced fluorescence quantum yield and a fluorescence color that could be adjusted by the mixing ratio from red to green and blue.

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This work was supported by CREST (JPMJCR20T4) and ACT-X (JPMJAX201J) from the Japan Science and Technology Agency (JST), and by Scientific Research (A) (JP16H02081), and Young Scientist (JP22K14656) from the Japan Society for the Promotion of Science (JSPS), Ogasawara Foundation, Ministry of Science and Technology Taiwan (110-2221-E-007-006-MY3 and 110-2113-M-007-013-MY3).

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HY, MH and YY conceived the idea and designed the experiments; CL, C-HJ, M-CT and MH conducted the organic synthesis; YI and HY conducted the self-assembly; and HY, MH, and YY prepared the manuscript.

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Correspondence to Masaki Horie or Yohei Yamamoto.

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The authors declare no competing interests.

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Ihara, Y., Yamagishi, H., Lin, C. et al. Hydrothermal crosslinking of poly(fluorenylamine) with styryl side chains to produce insoluble fluorescent microparticles. Polym J 55, 547–553 (2023).

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