Triple redox/temperature responsive diselenide-containing homopolypeptide micelles and supramolecular hydrogels thereof

Stimuli-responsive polypeptides are receiving much attention for drug delivery systems and tissue engineering scaffolds; however, it is challenging to construct multiple-responsive polypeptides and one-component polymeric hydrogels. Herein, a novel type of triple redox/temperature-responsive diselenide-containing poly(methoxydiethylene glycol-l-glutamate) homopolypeptide was facilely synthesized by selenocystamine-initiated ring-opening polymerization in DMF at 30 degrees C, and their chemical structures and physical properties were fully characterized by means of H-1 NMR, GPC, FT-IR, WAXD, and CD. They self-assembled into spherical micelles in aqueous solution, which possess a lower critical solution temperature, redox-responsiveness inherited from diselenide bond, and the triple stimuli-sensitive self-assembly behaviors, as characterized by means of turbidity, DLS, TEM, and zeta potential measurements. The diselenide-containing homopolypeptides formed supramolecular hydrogels at room temperature, exhibiting a thermal gel-sol transition. The rheological tests evidence that the mechanical modulus of the hydrogel is independent of angular frequency within 100 rad/s and at 25 degrees C, in which the storage modulus of G is order of magnitude greater than the loss modulus of G, displaying a solid-like elastic behavior. Moreover, the mechanical modulus of the hydrogel can be tuned by changing the chain length of the homopolypeptide, the 10-mM 1,4-dithiothreitol (DTT) reduction, and 1 mM H2O2 oxidation, respectively. Consequently, this work provides a simple strategy to fabricate triple-stimuli responsive polypeptide micelles and one-component hydrogels. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1067-1077