Synthesis and characterisation of novel polypeptide materials by the polymerisation of N-carboxyanhydrides

Abstract

Advances in controlled polymerisation strategies over the last decade have allowed chemists to create materials of defined structure and architecture to probe and mimic the greatest chemist of them all ― mother nature. In this work poly-peptides have been synthesised by the polymerisation of amino acid N-carboxy anhydrides without the need for transition metal catalysts. Application of stringent reaction conditions and high-purity monomers allowed control to be imposed on the system and a series of novel homo- and block co-polypeptides to be synthesised and characterised fully. Their ability to assemble into nano- and micro-structures, apparently directed by ß-sheet stacking has been investigated in the solid state by WAXS, electron microscopy and AFM. Organo-gelation was also observed and studied in dilute concentrations of the block-co-poly-peptides. A new and improved synthesis for 7V-carboxy anhydrides bearing carbohydrate motifs was developed without the need for extensive protecting group manipulation or toxic mercury compounds, which were used previously. Finally the possibility of using water soluble polypeptides and vinyl derived polymers as mimics of antifreeze glyco-proteins in the inhibition of the recrystallisation of ice has been evaluated. This showed that not all of the complex structural features present in the native protein are required to retain at least some activity.