Secondary Structure-Governed Polypeptide Cross-Linked Polymeric Hydrogels

Abstract

Modulation of the secondary structures of peptides gives rise to a range of natural peptide-based soft materials with outstanding mechanical properties. Here, we discuss detailed insights on how the secondary structure of tailor-made polypeptides governs the mechanical properties of polymeric hydrogels. To this end, we developed a series of polymeric hydrogels cross-linked by poly­(3-propyl-acrylate-glutamine) with tailorable secondary structuresα-helices and random coils. Interestingly, the hydrogels cross-linked by the α-helical cross-linker exhibit a high tensile strength and toughness because of the cooperative intramolecular hydrogen bonding along the polypeptide backbone. Furthermore, the α-helices endow the hydrogels with high resilience and rapid recovery because of their reversible cooperative hydrogen bonding. In contrast, the hydrogels cross-linked by the random coil cross-linker show inferior tensile strength and toughness. Our study establishes quantitative nanoscale/macroscale structure–property relationships in polymeric hydrogels and has important implications for the rational design of soft materials using polypeptides with a specific secondary structure.

Organobase 1,1,3,3-tetramethyl guanidine catalyzed rapid ring-opening polymerization of α-amino acid N-carboxyanhydrides adaptive to amine, alcohol and carboxyl acid initiators

“…Synthetic polypeptides, possessing similar structures to natural proteins, have attracted extensive interest due to their promising applications in fields such as tissue engineering, drug delivery, antimicrobial agents and batteries. [1][2][3][4][5][6][7][8][9][10][11] The ringopening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCA) enables large-scale synthesis of polypeptides. [12][13][14][15][16] To date, different initiator/catalyst systems and polymerization conditions have been developed for the controlled and rapid polymerization of NCAs, including Ni/Cobased organometallic catalysts, 17 high vacuum, 18 low temperature, 19 ammonium salts, 20,21 primary amine rare earth hydrochloride, 22 a nitrogen flow, 23 metal-based hexamethyldisilazides, [24][25][26] trimethylsilyl amines and sulfides, [27][28][29] multi-amines, 30,31 carbenes, 32 fluorinated alcohols 33 and tetraalkylammonium carboxylate.…”

Chirality-Governed UCST Behavior in Polypeptides

“…In addition to the sequence, chirality is another crucial intrinsic characteristic of polypeptides, which not only regulates the formation of life but also influences the mechanical performance and biological response of polypeptide-based materials. The chirality has been utilized to fabricate human-made materials to imitate the natural materials. − Despite the important role of chirality playing in polypeptide-based materials, the relationship between their chirality and UCST behavior has heretofore been scarcely investigated.…”

Synthesis and Hydrogelation of Star-Shaped Graft Copolypetides with Asymmetric Topology

“…Amongst all types of hydrogels, peptide-based hydrogels have self-assembly ability for hydrogel formation through hydrogen bonding, aromatic (cation-π, π-π), and hydrophobic/hydrophilic interactions [ 12 , 13 , 14 , 15 ]. Additionally, peptide segments can adopt secondary conformations (random coil, β-sheet/β-turn) inside their gel network to enhance the mechanical properties of hydrogels [ 16 , 17 , 18 , 19 , 20 ]. As a type of synthetic hydrogel, polypeptides can modify the characteristics of hydrogels by varying the functional groups on the side chain or the chain composition on the backbone [ 21 , 22 , 23 ].…”