Devices that release pain killing drugs in response to the amount of strain placed on them could soon be less science fiction and more science fact thanks to researchers from France.

Philippe Lavalle and co-workers from INSERM and the University Louis Pasteur, Strasbourg, have shown that certain types of polyelectrolyte thin films develop small pores when stretched and then, if the correct formulation is chosen, automatically heal themselves when allowed to relax. Such films could eventually allow drug delivery implants that release pain killing drugs depending on how much strain is placed upon them.

'Polyelectrolyte multilayers are thin films made up of alternating layers of polyanions and polycations and they can be used to form active coatings that respond to various stimuli including temperature, light and pH,' Lavalle explained. 'The films we describe have potential in, for example, the development of drug release devices, biomimetic membranes, vascular prostheses and fuel cells.'

Helmuth Möhwald from the Max-Planck Institute of Colloids and Interfaces in Potsdam, Germany, said 'This is the first report on the effect of mechanical stimuli on polyelectrolyte thin films. One can imagine many applications for such films including both hi-tech drug delivery devices to the more low-tech but extremely high volume applications such as releasing perfume from fabric as it is stretched.'

'In the future we would like to develop a system that works as a nanovalve and will allow, for example, small peptides to pass through,' said Lavalle.

Stephen Davey