Palladium method targets drugs where they are needed

Chemists have developed a way to synthesise drugs inside the human body at the precise site where they are required using nanoparticles of palladium.

The method offers a way of targeting drugs where they are needed and could safeguard the rest of the patient’s body and help curb side effects associated with chemotherapy.

The researchers came up with a way of exploiting palladium as a catalyst — a method that is widely used in industrial reactions but has not so far been applied in biochemical systems.

‘We are doing new chemistry that has never been done before inside a cell,’ said Emma Johansson of Edinburgh University, who worked on the project.

‘Normally when you synthesise drugs, you do that in a chemistry lab at really high temperatures of around 130°C and then you give it to the patient. We managed to it do at 37°C inside the cell.’

Regular chemotherapy drugs circulate freely in the bloodstream and attack rapidly dividing cells, including cancer cells.

However, they also attack normal, healthy dividing cells, such as those in bone marrow and the digestive tract, causing a range of side effects.

The current system aims to get around this by combining palladium and a precursor from a cancer drug at a targeted location.

In theory, patients would be injected with the precursor chemotherapy, or pro-drug, that is entirely inert and inactive, and can circulate around the body with no ill effects. The area doctors wished to target — in the case of cancer patients, the tumour — would then be injected with the palladium nanoparticles.

When the palladium and the pro-drug encountered each other, a reaction would take place allowing the synthesis of an active form of the drug that could then take effect and kill the cancer cells.

In the preliminary study, cytotoxicity, which is a way of measuring the effectiveness of chemotherapy, was increased sevenfold relative to regular chemotherapy delivery.

The work was carried out in collaboration with the Universiti Kebangsaan Malaysia. It was supported by the EPSRC, the Royal Society, the government of Malaysia and the Swiss National Science Foundation.