Polypeptide-based materials prepared by ring-opening polymerisation of anionic-based alpha-amino acid N-carboxyanhydrides: A platform for delivery of bioactive-compounds

Polymerisation of alpha-amino acid N-carboxyanhydrides (NCAs) is one of the most common techniques to prepare synthetic polypeptides. Of special interest are the NCAs derived from alpha-amino acids, L-aspartic acid and L-glutamic acid, since most investigations have been focused on their use to synthesise multiblock copolypeptides or hybrid synthetic polypeptide-polymers to design excipients suitable for delivery of bioactive compounds. This perspective highlights advantages of using L-aspartic acid and L-glutamic over other natural alpha-amino acids in that their pendant carboxyl group serves as a reactive handle for coupling a variety of reactive groups, and because the resulting polypeptides have the ability to adopt secondary structures. In addition, recent progress in the ring-opening polymerisation of NCAs will be discussed. Throughout, we provide representative examples that shed light on the NCAs polymerisation process, and we finally share our perspectives concerning the practical use of anionic alpha-amino acids as building blocks for future investigations.