Illuminating changes

Piersandro Pallavicini and colleagues at the University of Pavia, Italy, have developed a system for fluorescence signalling within a pH range rather than at a specific pH value. Efficient pH signalling in aqueous solutions is required during many chemical and biological processes and fluorescence is often used to observe changes in pH, but previously only changes at specific pHs could be measured.

Using a fluorescence indicator, a copper coordination complex and easily synthesised amine ligands, ’on-off-on’ fluorescence changes could be observed under acidic, neutral and basic conditions. By changing the ligand used, the pH region at which the fluorescence indicator did not fluoresce could be altered.

’Many biological processes take place only in limited pH ranges, and thus it could be useful to have tools to signal if the pH of the solution is within a predetermined window,’ says Pallavicini.

The team is now working on a probe version of the technique that can be added or removed from a sample as required.

Andrew West