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PH/temperature sensitive chitosan-g-(PA-PEG) aqueous solutions as new thermogelling systems
- PH/temperature sensitive chitosan-g-(PA-PEG) aqueous solutions as new thermogelling systems
- Jang J.H.; Choi Y.M.; Choi Y.Y.; Joo M.K.; Park M.H.; Choi B.G.; Kang E.Y.; Jeong B.
- Ewha Authors
- SCOPUS Author ID
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- Journal of Materials Chemistry
- vol. 21, no. 14, pp. 5484 - 5491
- As a new thermal gelling polymer aqueous solution, we are reporting a poly(ethylene glycol)-poly(alanine) grafted chitosan (CS-g-(PA-PEG)) system. The sol-gel transition temperature and the modulus of the in situ-formed thermal gel at 37°C changed 17 → 27 →32°C and 396 → 241 → 43 Pa, respectively, as the pH increased from 3.0 to 6.5 and to 9.0. The mechanism of such a pH/temperature sensitive behaviour of the CS-g-(PA-PEG) aqueous solution was investigated by studying changes in the conformation of chitosan, polyalanine and PEG of the CS-g-(PA-PEG). As the temperature increased, ammonium groups of the chitosan partially deprotonated to a neutral form, the α-helical content of the polyalanine increased and molecular motion of the PEG decreased. Such changes cooperatively increase the hydrophobicity and viscosity of CS-g-(PA-PEG), resulting in the sol-gel transition of the polymer aqueous solution with increasing temperature. As the pH increased, ammonium groups of the chitosan deprotonated to a neutral form and the α-helical content of polyalanine decreased, which induce a change in the nanoassembly of the polymer. CS-g-(PA-PEG) significantly increased the gel modulus of a previously reported PEG grafted chitosan (CS-g-PEG) thermal gel by incorporating the α-helical polyalanine moieties between CS and PEG. The CS-g-(PA-PEG) could be a promising biomaterial as a new robust thermogel with pH and temperature sensitivity. © 2011 The Royal Society of Chemistry.
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