Angewandte Chemie International Edition
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
For full article and contact information, see Angew. Chem. Int. Ed. 2002, 41 (16), 2957 - 2960
Spirelli and Tagliatelle in the Nano World
Oligopeptide-surfactant hybrids as building blocks
for biologically active, nanostructured materials?
It seems that scientists, too, enjoy eating Italian food; how else would they come up with such names as "spirelli" and "tagliatelle" for tiny structures they discover with their electron and atomic-force microscopes? Markus Antonietti and Sascha General have recently also stumbled across such nanonoodle analogs. These chemists from the Potsdam Max-Planck-Institute for Colloid and Interface research are working on the synthesis of new types of materials with highly ordered structures in the nanometer range. Such materials have many interesting opto-electronic properties and could be used for nanotechnology. Antonietti and General now also want to develop nanostructures with biochemical functionality.
Oligopeptides, short protein chains, are good candidates to be bio-building blocks for nanostructures. However, extensive artificial structures made of oligopeptides have so far not been accessible. The Potsdam researchers selected oxidized glutathion for their investigations. This compound consists of two peptide trimers that are connected to each other by a bridge made of two sulfur atoms, forming an H. Glutathion is a co-enzyme and takes part in a variety of important cellular functions, such as detoxification reactions.
Antonietti and General found a trick by which they could encourage their peptide-"H" to undergo a self-organization process; they add some surfactant or lipid molecules, which consist of a negatively charged, hydrophilic "head" and a hydrophobic (water-repelling) "tail". With their heads, these molecules attach to the positively charged functional groups on the H-shaped peptides. Once in this hybrid state, the peptides are no longer only soluble in water, but also in organic solvents. Groups of about ten hybrid building blocks aggregate into long bands, which then twist into spirals like wood shavings - or "spirelli". If the solvent is evaporated off, transparent films are formed, which are flexible but very hard. These films have a highly ordered nanostructure; the bands are arranged - not in a spiral, but flat - into a lamellar band structure, which is named the "tagliatelle phase", after the flat Italian noodles it resembles.
"This manner of forming biologically active films by self-organization could be used for the development of such things as glues for closing wounds or new forms of treatment involving the controlled administration of peptide agents," says Antonietti.