Measurement of the dynamic behavior of thin poly(N-isopropylacrylamide) hydrogels and their phase transition temperatures measured using reflectometric interference spectroscopy

  • Fuminori Okada
  • Yoshikatsu AkiyamaEmail author
  • Jun Kobayashi
  • Hidetaka Ninomiya
  • Hideko Kanazawa
  • Masayuki Yamato
  • Teruo Okano
Research Paper
Part of the following topical collections:
  1. Engineered Bioinspired Nanomaterials


Temperature-responsive cell culture surfaces prepared by modifying tissue-culture polystyrene with nanoscale poly(N-isopropylacrylamide) (PIPAAm) hydrogels are widely used as intelligent surfaces for the fabrication of various cell sheets that change with temperature. In this work, the characteristics of nanoscale PIPAAm hydrogels were phenomenologically elucidated on the basis of time-dependent surface evaluations under conditions of changing temperature. Because the dynamic characteristics of the nanoscale hydrogel did not exhibit good performance, the nanoscale PIPAAm hydrogel was analyzed by monitoring its temperature-dependent dynamic swelling/deswelling changes using reflectometric interference spectroscopy (RIfS) on an instrument equipped with a microfluidic system. RIfS measurements under ambient atmosphere provided the precise physical thickness of the dry PIPAAm hydrogel (6.7 nm), which agreed with the atomic force microscopy results (6.6 nm). Simulations of the reflectance spectra revealed that changes in the wavelength of the minimum reflectance (Δλ) were attributable to the changes in the refractive index of the thin PIPAAm hydrogel induced by a temperature-dependent volume phase transition. The temperature-dependent Δλ change was used to monitor the swelling/deswelling behavior of the nanoscale PIPAAm hydrogel. In addition, the phase transition temperature of the thin PIPAAm hydrogel under aqueous conditions was also determined to be the inflection point of the plot of the change in Δλ as a function of temperature. The dynamic behavior of a thin PIPAAm hydrogel chemically deposited on a surface was readily analyzed using a new analytical system with RIfS and microfluidic devices.


Temperature-responsive polymer Poly(N-isopropylacrylamide) Thin hydrogel Reflectometric interference spectroscopy Phase transition temperature Electron beam irradiation Bioinspired nanomaterial 



Part of this work was financially supported by a Grant-in-Aid for Scientific Research (Grant No. 23106009) in Innovative Areas “Bio Assembler” (Area No. 2305) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. We are grateful to Mr. Sato and Mr. Tsutsumi, J. A. Woollam Japan Corporation, for measuring the refractive index of the thin PIPAAm hydrogels under aqueous conditions.

Supplementary material

11051_2015_2951_MOESM1_ESM.doc (1.1 mb)
Supplementary material 1 (DOC 1078 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Fuminori Okada
    • 1
    • 2
  • Yoshikatsu Akiyama
    • 2
    Email author
  • Jun Kobayashi
    • 2
  • Hidetaka Ninomiya
    • 1
  • Hideko Kanazawa
    • 3
  • Masayuki Yamato
    • 2
  • Teruo Okano
    • 2
  1. 1.Konica Minolta, INC.Hino-shiJapan
  2. 2.Institute of Advanced Biomedical Engineering and ScienceTokyo Women’s Medical University (TWIns)Shinjuku-kuJapan
  3. 3.Faculty of PharmacyKeio UniversityMinato-kuJapan

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