A new type of catalyst assembles cancer drugs from benign components, and can work inside laboratory animals.

Some drug molecules can be split into smaller parts that are then equipped with specific chemical groups. These groups allow the components to be put back together in a 'click' reaction in the presence of a catalyst. This could reduce the side effects of cancer drugs by rendering them inactive until they reach the tumour where they are reassembled — a step that previously required a toxic copper-ion catalyst. Mark Bradley of the University of Edinburgh, UK, and his colleagues developed a non-toxic alternative by growing copper nanoparticles inside a polymer resin. Their catalyst assembled an anti-tumour drug that killed cancer cells in culture.

The catalyst was also active and non-toxic in tests in zebrafish embryos.

Angew. Chem. Int. Edn http://doi.org/f3s7ct (2016)