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The University of Southampton

Biodegradable Injectable Polymers as Smart Biomedical Materials Seminar

25 July 2018
Building 27, Room 2003 Chemistry University of Southampton SO17 1BJ

For more information regarding this seminar, please email Prof. Steve Goldup at .

Event details

Prof. Yuichi Ohya presents a seminar as part of the Functional Inorganic, Materials and Supramolecular Chemistry sections seminar series.

Aqueous solutions of some amphiphilic block copolymers are known to exhibit sol-to-gel transitions in response to temperature increase. Such thermo-gelling polymer systems have attracted great attention as injectable polymers (IPs) for biomedical applications, such as drug delivery system, scaffold for tissue engineering, anti-adhesive on surgical operation, and so on. We have studied on thermo-gelling systems using biodegradable block copolymers of PEG and aliphatic polyesters.1) Most of temperature-responsive IP systems reported exhibit rapid sol-to-gel transitions to form hydrogels by the physical (non-covalent) cross-linking of polymers. However, one of the practical problems for these systems is the short duration time of the gel state in the body. The formed hydrogel tends to revert to the sol state within a short period (typically less than 24 h) where a large amount of body fluid exists, because the main driving force of gelation in these systems is a non-covalent hydrophobic interaction and gel formation is an equilibrium process. This property is one of the obstacles of biodegradable IP systems for clinical application as implant biomedical materials. We recently reported biodegradable temperature-triggered covalent gelation systems exhibiting longer and controllable duration time of the gel state utilizing succinimide-amine coupling2) or thiol-ene reaction3,4). We synthesized a tri-block copolymer of poly(caprolactone-co-glycolic acid) and PEG (tri-PCG) and attached acryloyl groups on both termini (tri-PCG-Acryl). Tri-PCG micelle solution containing hydrophobic hexa-functional polythiol and tri-PCG-Acryl micelle solution were mixed. The obtained solution was still sol state after mixing, and exhibited an irreversible sol-to-gel transition in response to temperature. The duration time of the gel state in vitro (in PBS) and in vivo (after subcutaneous implantation in rat) could be altered from 1 to 90 days just by changing the mixing ratio. Moreover, we investigated the potential utility of the system as sustained drug releasing devices,5) anti-adhesive materials and stem cell delivery devices.


[1].  a) K. Nagahama, A. Takahashi, Y. Ohya, React. Funct. Polym., 73, 979 (2013).
       b) K. Nagahama, T. Ouchi, Y. Ohya, Adv. Funct. Mater., 18, 1220 (2008).
       c) K. Nagahama, Y. Ohya et al., J. Polym. Sci. Part A Polym. Chem., 46, 6317 (2008).
       d) K. Nagahama, Y. Ohya et al., Polymer, 50, 3547 (2009).  
       e) A. Takahashi, Y. Ohya et al., J. Biomat. Sci. Polym, Ed., 25, 444 (2014).
       f) A. Takahashi, Y. Ohya et al., Polym. Adv. Technol., 25, 1226 (2014).
       g) Y. Yoshida, Y. Ohya et al., Polym. J., 46, 632 (2014).
       h) Y. Yoshida, Y. Ohya et al., J. Biomat. Sci. Polym., Ed., 28, 1158 (2017).
       i) K. Takata, Y. Ohya et al., Polym. J., 49, 677 (2017).
[2]. Y. Yoshida, Y. Ohya et al., ACS Biomater. Sci. Eng., 3, 56 (2017).
[3]. Y. Yoshida, Y. Ohya et al., Biomat. Sci., 5, 1304 (2017).
[4]. Y. Yoshida, Y. Ohya et al., J. Biomat. Sci. Polym. Ed., 28, 1427 (2017).
[5]. K. Takata, Y. Ohya et al., Gels, 3, 38 (2017)

Speaker information

Prof Yuichi Ohya, Department of Chemistry and Materials Engineering, Kansai University, Collaborative Research Center of Engineering, Medicine and Pharmacology (CEMP), Kansai University, Suita, Osaka, Japan. Research interest: Smart biomaterials.

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