Lumiphore's patented lanthanide technology offers key advantages over current fluorescent systems:

• Long lifetimes and high quantum yields give high signal-to-noise ratio results and assay sensitivity significantly better than current fluorophores.
• Multiple lanthanide fluorophores (four different colors) enable up to four simultaneous assays.
• A large gap between excitation and emission energies means no self quenching and permits multiple excitation.
• Resistance to photo bleaching allows archiving of samples for improved quality control and for comparisons between old and new data.

The company has exclusive rights to patents owned by the University of California. These patents cover a proprietary shell around the lanthanide molecule that confers exceptional luminescence, brightness, stability and versatility. The two University of California inventors remain actively involved with Lumiphore. The company intends to pursue a patent strategy so that it will own patented technology for specific conjugation of the lanthanide compounds.

Luminescence

Luminescence describes any process in which energy is emitted from a material at a different wavelength from that at which it is absorbed. It is the preferred detection technology in biology, primarily because luminescent compounds can be manipulated easily in contrast to conventional radioactive labels. This general ease of use has led to the development of a variety of luminescent probe technologies. Light can be detected, quantified and localized with a wide range of established optical methods. The process can be automated with optical scanners, analysis software and well-plate readers. This ease of use has made luminescence the dominant detection platform in biological assays.

Lanthanides as Fluorophores

The most common source of luminescent probes is organic fluorophores, but the excitation of lanthanides (a group of fourteen heavy metals) is superior in several ways. However, since water molecules are very efficient at deactivating the lanthanide metal emission, the lanthanide metal must be protected in order to prevent loss in luminescence signal; this can be done using organic ligands (cages). Several development efforts, including a major program at Perkin Elmer, have attempted to develop such caged ligands.

Building cages that both protect the lanthanide from surrounding water molecules and efficiently deliver light energy to the lanthanide is a significant challenge. Drs. Kenneth Raymond, Stéphane Petoud and Jide Xu at University of California, Berkeley, made a significant breakthrough in designing isophthalamide-lanthanide and salicylamide-lanthanide complexes that combine the stability of organic fluorophores with the superior luminescent properties of lanthanides-a new ligand structure possessing properties required to obtain bright luminescence from the lanthanide ions. (The figure at left shows one of these ligands; the lanthanide is in the center of the complex.)