Feb 14, 2013
Upgraded silver nanoclusters benefit bioimaging
Over the past decade there has been more and more interest in the development of luminescent nanomaterials for a range of uses, including biomedical imaging, display and lighting applications. Recently, scientists based at the Leiden University Medical Centre and Utrecht University in the Netherlands, have been examining the performance of luminescent “noble” metal clusters. Thanks to the inert nature of the material and its ultra small size, the structures are potential biolabels.
Reporting their results in the journal Nanotechnology, the researchers conducted a detailed study on the influence of surface modifications on luminescent silver clusters. These silver clusters are composed of 25 atoms capped with dihydrolipoic acid (DHLA) and show a distinct absorbance spectrum with several sharp transitions.
The silver clusters reveal a relatively broad deep red luminescence with a quantum yield of 5% combined with a remarkably long luminescence lifetime of ~3 µs at room temperature. Both pH and the presence of coordinating ligands influence the absorbance spectra and luminescence intensity.
These modifications were seen to induce a strong increase in luminescence intensity up to 45% quantum efficiency, and the team concluded that the surface coordination of the silver clusters has a strong influence on the material’s optical properties.
The researchers presented their work in the journal Nanotechnology.
About the author
Patrick Chin is a researcher based at the Leiden University Medical Centre in the Netherlands.