Molecular ruler opens route to nanoscale design

Research lead

Researchers from Liverpool, London and Leeds universities in the UK, have developed a technique for examining self-assembled peptides on the surface of a gold nanoparticle, opening the way to a new method for designing and manufacturing nanomaterials.

The work was funded by Biotechnology and Biological Sciences Research Council (BBSRC) and led by Raphaël Lévy.

Whilst the technique of constructing nanoscale building blocks through initiating self-assembly of peptides on the surface of a gold nanoparticle can provide a massive number and diversity of new materials relatively easily, the challenge is to be able to examine the structure of the material.

Using a combination of chemistry and computer modelling, Lévy has measured the distance between the peptides as they sit assembled on the gold nanoparticle. The technique exploits the ability to distinguish between two types of connection or cross-link – intramolecular links joining different parts of the same molecule, and - intramolecular links that join together two separate molecules.

As two peptides get closer together there is a transition between these two different types of link. 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 interaction between peptides leads to a nanoparticle that is relatively organised, 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.

“By using a combination of chemistry and computer simulation we have been able to demonstrate a method by which we can start to see what is going on at the nanoscale,” said Levy.

Understanding how peptides self-assemble at the surface of a nanoparticle, opens up a route for the design and synthesis of nanoparticles with complex surfaces. Such particles could find applications in the biomedical sciences, for example to deliver drugs to a particular target in the body, or in diagnostic tests. In the longer term, these particles could be used as electronic components.