Macromolecular nano-objects from peptide-hybrid block copolymers

• Applicant: Professor Dr. Harm-Anton Klok
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2002 to 2008
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5381995

This proposal focuses on the design and preparation of macromolecular nano-objects of defined size and shape via self-assembly of peptide-based diblock copolymers in aqueous solution and covalent post-modification of the resulting supramolecular assemblies. The peptide segments of the block copolymers poses some unique features, including the ability to undergo directed hydrogen bonding interactions, to adopt defined secondary structures and to assemble into well-defined higher-order protein domain structures. In some cases, conformational changes by variations in environmental parameters can be used to reverse these assembly processes. This proposal seeks to explore these peculiar characteristics of the peptide blocks for the preparation of unprecedented supramolecular assemblies, which can be covalently captured and transformed into the targeted hybrid nano-objects. Two classes of block copolymer building blocks will be explored; one class composed of a hydrophobic poly(butadiene) or poly(isoprene) block and a hydrophilic peptide segment, and a second class comprised of a hydrophilic poly(ethylene glycol) block and a perfectly monodisperse peptide segment with a precisely defined amino acid sequence. The self-assembly of the first class of building blocks is primarily driven by the amphiphilic character of the block copolymers, whereas in the second case the formation of protein folding motifs provides a very specific driving force for self-assembly. For the preparation of nano-objects with geometries, crosslinking strategies will have to be developed that allow covalent capture of the supramolecular assemblies without affecting size or shape. Due to their well-defined geometry and the mechanical stability obtained after crosslinking, the nano-objects have the propensity to pack into predictable superlattices. Using various layer-by-layer assembly methods, it will be attempted to explore these characteristics of the nano-objects for the preparation of supramolecular materials with interesting optical or electro-mechanical properties and for the development of ultrathin hydrogel layers for biomedical purposes. It will be investigated to which extent conformational changes can be used to reversibly switch the non-linear optical and/or piezoelectric activity, to modulate the uptake and release characteristics and manipulate the swelling behaviour of these materials.

• DFG Programme: Research Grants
• International Connection: France, Switzerland
• Participating Person: Professor Dr. Sébastian Lecommandoux