Polypeptide materials: New synthetic methods and applications

A review of recent developments in polypeptide synthesis is provided. This article is focused on development of new materials based on polypeptides rather than on reproduction or applications of natural protein-based materials. Synthetic methods fall into two major categories: biological and chemical. The most successful biological approaches utilize cellular protein synthesis machinery to perform the task of assembling the polymeric molecules. Adaptation of this machinery for production of new, artificial polypeptide sequences and use of this machinery for incorporation of artificial amino acids into polypeptides have been the key recent contributions in this area. Advances in chemical polypeptide syntheses include new applications in solid and solution phase peptide coupling reactions as well as advances in the polymerization of a-amino acid-N-carboxyanhydride (NCA) monomers. The use of transition metal initiators in NCA polymerizations has allowed the preparation of very well defined homopolypeptides and may lead to facile routes into peptide block copolymer materials. The presence of stable, chiral structural elements in polypeptides results in self-assembly into ordered films, composites, and liquid crystals. If their sequences are designed and constructed properly, artificial polypeptides have considerable potential for use in construction of artificial tissues and implants, ordered inorganic/organic composites, and in medical diagnostics and biosensors.