Doughnut-shaped particles could help to reduce side effects from cancer treatments, says a team of scientists from the UK. 

Developed by a team fronted by Mark Bradley at the University of Edinburgh, the uniquely-shaped polystyrene particles can penetrate specific cell types in the body, and have a particular affinity for the liver. 'This opens up the possibility of using these particles to deliver therapeutics solely to the liver in cases of disease and could limit side effects associated with the treatment,' says Bradley. Side effects, such as hair loss in cancer treatment, can arise because drugs aimed at cancer cells may also affect similar cell types in other parts of the body.

Bradley explains that the team stumbled on the micro-doughnuts accidentally during their investigations. Whilst using a simple technique called dispersion polymerisation to grow small particles in a polymer mixture, they found that adding a small amount of dioxane to the usual ethanol solvent gave their surprise result. 'The particles' unique and highly uniform structure was immediately interesting to us and we considered the possible applications they might have,' says Bradley. 

Andy Sutherland, an expert in polymer chemistry, at Aston University in the UK, says the particles' selective cellular uptake is striking. 'By understanding the basis of this cellular choice it may, in the future, be possible to design polymer constructs that both target specific cell types and allow molecular cargoes to be imported into these cells for therapeutic, diagnostic and imaging applications.'

The team suggests it is the particles' shape that is responsible for their cell specificity. Their unusual shape and uniform, tiny size - thirty times smaller than a human hair - mean they could also be suitable in filtration and purification devices, for example, says Bradley. The next challenge will be to understand how the doughnuts form, he adds.

Katherine Davies