Abstract
Well-defined nanostructural control from biological motifs is gaining attention among materials scientists. We are reporting that the β-sheet structure of l-polyalanine plays a critical role in developing a fibrous nanostructure as well as the sol-to-gel transition of amphiphilic poly(ethylene glycol)-l/or dl-polyalanine diblock copolymers. l-isomers underwent transitions from random coils to β-sheets, and to nanofibers as the polymer concentration increased, whereas the dl-isomer remained as a random coil structure without developing any specific nanostructure. At high polymer concentrations, the aqueous polymer solutions underwent a sol-to-gel transition as the temperature increased, a so called reverse thermal gelation. The l-isomer with a preassembled β-sheet secondary structure facilitates the sol-to-gel transition rather than the dl-isomer with a random coil structure. Thus, only the l-isomer showed a sol-to-gel transition in the physiologically important range of 20-40 °C. This report provides fundamental information on the relationship between hierarchical structures of polypeptides and the thermosensitive sol-gel transition of the polypeptide aqueous solution.
Original language | English |
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Pages (from-to) | 2383-2387 |
Number of pages | 5 |
Journal | Soft Matter |
Volume | 4 |
Issue number | 12 |
DOIs | |
State | Published - 2008 |