When scientists make a new material on a nanoscale how can they see what’s been made? A team lead by a Biotechnology and Biological Sciences research Council (BBSRC) fellow has made a significant step toward overcoming this major challenge faced by nanotechnology scientists.

A team from the University of Liverpool, The School of Pharmacy (University of London) and the University of Leeds, show that they have developed a technique to examine tiny protein molecules called peptides on the surface of a gold nanoparticle. This is the first time scientists have been able to build a detailed picture of self-assembled peptides on a nanoparticle and it offers the promise of new ways to design and manufacture novel materials on the tiniest scale - one of the key aims of nanoscience.

Engineering new materials through assembly of complex, but tiny, components is difficult for scientists. However, nature has become adept at engineering nanoscale building blocks, e.g. proteins and RNA. These are able to form dynamic and efficient nanomachines such as the cell’s protein assembly machine (the ribosome) and minute motors used for swimming by bacteria. The BBSRC-funded team, led by Dr Raphaël Lévy, has borrowed from nature, developing a way of constructing complex nanoscale building blocks through initiating self-assembly of peptides on the surface of a metal nanoparticle.

Using a chemistry-based approach and computer modelling, Dr Lévy has been able to measure the distance between the peptides where they sit assembled on the gold nanoparticle.

The technique exploits the ability to distinguish between two types of connection or ‘cross-link’ - one that joins different parts of the same molecule (intramolecular), and another that joins together two separate molecules (intermolecular). As two peptides get closer together there is a transition between the two different types of connection. Computer simulations allow the scientists to measure the distance at which this transition occurs, and therefore to apply it as a sort of molecular ruler. Information obtained through this combination of chemistry and computer molecular dynamics shows that the interactions between peptides leads to a nanoparticle that is relatively organized, but not uniform. This is the first time it has been possible to measure distances between peptides on a nanoparticle and the first time computer simulations have been used to model a single layer of self-assembled peptides.

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