Facile Synthesis of High Molecular Weight Polypeptides via Fast and Moisture Insensitive Polymerization of α-Amino Acid N-Carboxyanhydrides

Abstract

Polypeptides have been widely utilized in the fields of biomaterials and biomedicine. Ever since N-carboxyanhydride (NCA) was reported by Hermann Leuchs in 1906, ring-opening polymerization of NCAs has been extensively used to prepare polypeptides. Despite continuous innovations, it is still challenging to synthesize polypeptides in high molecular weight efficiently. To address this challenge, we developed KHMDS/NaHMDS initiated fast NCA polymerization that is also moisture tolerant, open-flask amenable and terminal tunable. This NCA polymerization was able to proceed in most common solvents and meet the solubility requirement of variable NCA monomers and corresponding polypeptides. KHMDS can initiate γ-benzyl-L-glutamate-N-carboxyanhydride (BLG NCA) polymerization in a reaction rate 92 times faster than does hexylamine and 80 times faster than does triethylamine. This NCA polymerization also demonstrated easy and fast synthesis of gram-scale long chain polypeptides in an open flask.