By the time Raphael Levy arrived at the University of Liverpool in 2002 to begin a postdoc, the collaboration behind his recent publication (ACS Nano 3, 2461–2468; 2009) had already begun. Mathias Brust from the chemistry department and David Fernig from the school of biological sciences had been working together on the use of noble metal nanoparticles for sensing. Levy brought two biologists — Violaine Sée and Michael White — into the fold, along with Brahim Lounis, a physicist from the University of Bordeaux who had developed photothermal microscopy for imaging metallic nanoparticles. The collaboration was later joined by Ian Prior, Dan Rigden, experts on electron microscopy and bio-informatics respectively, and others.

In their experiments Levy and his colleagues watched as gold nanoparticles covered with peptides were swallowed by mammalian cells (a process called endocytosis). Whereas electron microscopy showed that the nanoparticles entered and were stable inside the cells, fluorescence probing revealed that the peptide layer was being destroyed. This was due to the cleaving action of an enzyme called cathepsin L. Bioinformatics tools indicated that this enzyme is capable of cleaving more than a third of the human proteome, making the phenomenon a rather general one. However, the team were also able to demonstrate how to inhibit the cleaving process. The results have implications for nanoparticle-based drug-delivery and imaging applications.

Levy stresses the importance of maintaining a space where discussions between scientists can take place. The group at Liverpool conducted a monthly bionano meeting, out of which several new ideas emerged. Although such meetings can be successfully arranged in most collaborations, it may be harder to follow another of Levy's recommendations: “marry a scientist from another discipline”. Levy and the first author on the paper, Violaine Sée, are life partners.