Use of Multiblock Polypeptide Architectures to Control Chain Self-Assembly and Hydrogel Properties

摘要

Using transition metal catalysis chemistry for the polymerization of alpha-amino acid-N-carboxyanhydrides (NCAs), we have prepared amphiphilic diblock, triblock and pentablock copolypeptides containing hydrophilic and hydrophobic segments. The hydrophilic chains are composed of either cationic or anionic residues, and the hydrophobic chains are composed of natural non-polar amino acid residues such as leucine, valine and phenylalanine. Our group has developed hydrogels based on amphiphilic d i - and t r i b l o c k copolypeptides, K_mL_n and K_mL_nK_o, which utilize the assembly of wholly hydrophobic alpha-helical poly-L-leucine segments (L) to drive gel formation in water. The presence of highly charged, hydrophilic poly-L-lysine segments (K) causes these assemblies to form long tape-like fibrils that branch and tangle to form hydrogel networks. We now report on a series of amphiphilic pentablock copolypeptides, K_mL_nK_oL_nK_m, where the intramolecular assembly of two hydrophobic domains connected by a variable linker was found to enable precise tuning of assembly morphology and hydrogel properties.