A film that releases one of the body's signalling molecules could find uses from biochemical studies to new materials, say scientists in Italy. Ludovico Valli and co-workers at the Universities of Salento and Catania, have developed a multilayer film that releases nitric oxide (NO) under light stimuli.

Shining light on multilayer films releases NO on demand

NO is more than just an environmental pollutant, it also plays a vital role in a range of biological processes, including blood vessel dilation, neurotransmission and hormone secretion. Therefore, compounds that deliver NO are of great interest for biochemical research. 'But only a limited number of NO photodonors have been integrated in appropriate materials,' says team member Salvatore Sortino, explaining the group's motivation.

The researchers incorporated a light-sensitive NO donor molecule into multilayer films. They found that the films were stable in the dark, but when illuminated emitted a nanomolar amount of NO. The NO reservoir size can be varied by changing the number of layers. Also, increasing the films' light exposure times increases the levels of NO delivered. 'This offers the possibility of accurately controlling NO dosage exclusively by light,' says Sortino, 'making the films ideal for potential studies in biochemical research where precise control of NO release is required.'

Alberto Credi, of the University of Bologna, Italy, whose research interests include photoactive devices and machines, agrees. 'Several molecules will release nitric oxide under light irradiation in homogeneous solution,' says Credi. 'But integrating them into these films represents a significant step towards molecule-based materials and devices for NO delivery with spatial and temporal control.'

Vikki Chapman