The synthesis and application of stimuli-responsive polymer materials have been extensively studied. Among stimuli-responsive polymers, thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) is the most widely investigated. PNIPAAm-based polymers undergo a reversible hydrophilic/hydrophobic phase transition in response to temperature. In addition, by introducing sites that are responsive to physical and chemical stimuli into PNIPAAm-based polymers, they also undergo phase transitions in response to stimuli, such as light, pH, oxidation/reduction, and enzyme activity. In this focus review, recent advancements in the applications of stimuli-responsive polymers based on PNIPAAm in biomedical fields are summarized, with an emphasis on our own research. In particular, a summary of the design of polymers for application in the separation and purification of (bio)pharmaceutical products and controlled cellular uptake is provided. First, temperature-responsive chromatography with PNIPAAm-modified silica beads is introduced. Thereafter, temperature- and pH-responsive polymers based on PNIPAAm used in imaging and drug delivery applications are discussed. Finally, the conclusions are presented, and future perspectives for the biomedical applications of stimuli-responsive polymers are discussed.
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This study was partly supported by a Grant-in-Aid for Scientific Research for Research Activity-Career Scientists (Grant No. 19K16339), Grant-in-Aid for Scientific Research (C) (Grant No. 21K06495) from the Japan Society for the Promotion of Science (JSPS), and by the Program for the Advancement of Next Generation Research Projects (Type C) at Keio. I would like to thank Editage (www.editage.jp) for their English language editing services.
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Hiruta, Y. Poly(N-isopropylacrylamide)-based temperature- and pH-responsive polymer materials for application in biomedical fields. Polym J 54, 1419–1430 (2022). https://doi.org/10.1038/s41428-022-00687-z