Gelation of Helical Polypeptide-Random Coil Diblock Copolymers by a Nanoribbon Mechanism

Autor: Chiyoung Park, Mitchell A. Winnik, Kyoung Taek Kim, Ian Manners, Guido W. M. Vandermeulen, David A. Rider, Chulhee Kim
Rok vydání: 2005
Předmět:
Zdroj: Angewandte Chemie. 117:8178-8182
ISSN: 1521-3757
0044-8249
DOI: 10.1002/ange.200502809
Popis: The polypeptide poly(g-benzyl-l-glutamate) (PBLG) serves as a model rod-like polymer in solution and in the solid state because of its rigid a-helix conformation. The stiff rod-like conformation of the PBLG helix is a crucial prerequisite for its unique solution behavior such as liquid crystalline ordering and thermoreversible gelation. Nematic ordering (orientational order of rod-like molecules) is responsible for the thermoreversible gelation of PBLG in dilute solution. Diblock copolymers of PBLG and flexible organic polymers are unable to form a nematic phase due to the presence of a block with a bulky random-coil conformation. Here we report the discovery of thermoreversible gelation of diblock copolymers of PBLG in dilute solution which has not been observed previously despite many studies of such materials. We also explain the gel formation of PBLG-based diblock copolymers in solution by a mechanism which is distinct from the current understanding of PBLG self-assembly. Based on our findings, we describe the formation of self-assembled functional scaffolds with precisely aligned fluorescent labels. The results illustrate a novel and general mode of self-assembly for block copolymers of PBLG and presumably other helical polypeptides and demonstrate an attractive new approach to nanostructured supramolecular materials derived from biological and synthetic polymers. Our initial studies involved the synthesis of poly(ferrocenylsilane)-b-poly(g-benzyl-l-glutamate) (PFS-b-PBLG), conjugates of an organometallic polymer and polypeptides with narrow molecular weight distributions (Figure 1a, Table 1).
Databáze: OpenAIRE