Scale‐up Efficient Synthesis of α‐Poly(L‐lysine)†

Abstract

Comprehensive Summaryα‐Poly(L‐lysine) (α‐PLL) is a water‐soluble cationic biopolymer containing the monomeric unit α‐L‐lysine, which not only possesses excellent intrinsic properties but also can be modified via facile reactions between the side amine groups and many other functional moieties. Ring‐opening polymerization (ROP) is the most prevalently used technique for the synthesis of PLL‐based polypeptides, which involves initial conversion of the ε‐primary amine‐protected α‐L‐lysine to the L‐lysine NCA monomer. However, obtaining N‐carboxyanhydrides (NCAs) in high purity has been a formidable challenge for over 50 years, let alone the large‐scale synthesis. Herein, we show an unprecedented scale‐up synthesis of L‐Cbz‐LysNCA monomer and its polymers, generating linear α‐poly(L‐lysine) with molecular weight (MW) up to 13.4 kDa. This easy operated scale‐up strategy will lay the foundations for the industrial preparation of L‐Cbz‐LysNCA and its polymers, and further extend the realm of existing applications, offering a paradigm for scale‐up synthesis of other polypeptides.