α-Amino acid N-thiocarboxyanhydrides: A novel synthetic approach toward poly(α-amino acid)s

Poly(alpha-amino acid)s, containing amino acid repeat units, are remarkable biomaterials with similar structures to protein, which are mainly synthesized by solid phase peptide synthesis, ring opening polymerization of N-carboxyanhydrides, polymerization of activated urethane derivatives of alpha-amino acids and so on. alpha-Amino acid N-thiocarboxyanhydride (NTA) and N-substituted glycine N-thiocarboxyanhydride (NNTA) have recently emerged as a subject of scientific interest due to their easy synthesis and purification in open air, long shelf-life and well controlled polymerization to produce poly(alpha-amino acid)s. In this feature article, we review the history and the recent development on the design of NTA monomers, and summarize the recent advances in poly(alpha-amino acid)s synthesis through ring-opening polymerization of NTA and NNTA by using different initiators and reaction mediums. We also highlight the applications of poly(alpha-amino acid) materials resulting from NTA polymerization.