Effect of tethered sheet-like motif and asymmetric topology on hydrogelation of star-shaped block copolypeptides

Abstract

To study the hydrogelation and self-assembly ability of the star-shaped diblock copolypeptides, 6-armed and 12-armed block copolypeptides comprised of poly- l -Lysine (PLL) as the first block and separately tethered with different hydrophobic, sheet-like oligopeptides (β-motifs) were synthesized using polyglycerol dendritic initiators. The hydrogelation of these samples was driven by the various interactions and amphiphilic balances in the polypeptide assemblies, showing a strong dependence on arm number and β-motif. The incorporation of β-motifs could facilitate hydrogelation and the hydrogel mechanical properties could be tuned by varying the tethered β-motif. Moreover, the star-shaped block copolypeptides with a symmetric topology demonstrated a better hydrogelation ability than those asymmetric counterparts possibly due to their more efficient packing. The tethered β-motif strongly influenced both the molecular assembly and micro-/macroscopic structures. This study illustrated the tunability of polypeptide hydrogels by varying the arm number and tethered β-motif as well as the polypeptide chain symmetry. • Hydrogelation was driven by the various interactions and amphiphilic balances in the polypeptide assemblies. • Hydrogelation of these block copolypeptides showed a strong dependence on arm number and β-motif. • Polypeptides using asymmetric PGD G1 and G2 initiators exhibited lower efficiency in packing and hydrogelation. • Hydrogel molecular packing and mechanical properties depended on the arm number, chain symmetry and tethered β-motif.