Chemical wrapping enhances the effectiveness of luminescent probes used in medical imaging, say chemists in Switzerland. 

Claude Piguet at the University of Geneva and colleagues sandwiched lanthanide ions between two chromium ions, which were all wrapped in a helical array of ligands.  Lanthanide ions can act as near-infrared (near-IR) light emitters. These emitters are useful in non-invasive medical imaging applications because near-IR rays pass through human tissue more readily than visible light.

According to Piguet, the high stability of the structured arrangement of the lanthanide ions, combined with the prospect for future fine-tuning, could open the door to the preparation of strongly luminescent systems.

Piguet said his motivation for the work came from the 'desperately short lifetimes of lanthanide-based near-IR emitters used in medical and biological fluoroimmunoassays'. He claims that the work developed here is a first step toward solving this problem.

Michael Ward at the University of Sheffield, UK, said Piguet's findings are of significance from both a structural and photophysical viewpoint. The chemical strategy used here should 'provide access to materials showing unusual photophysical properties such as light up- and down-conversion,' said Ward.

Alan Holder