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T-00235: Lanthanide Complexes for Biomedical Imaging

Background: Bioimaging can visualize the location, size, or shape of targets by recording the fluorescence of an optical probe using confocal fluorescence microscopes. Complexes of lanthanide ions, such as ytterbium (III) have been proposed as alternative and improved optical probes, however, the key challenge for their applications in bioimaging is the need of a suitable chromophore that is capable of sensitizing lanthanide emission efficiently under long wavelength excitation.

Description: In chemical and bioassay applications the lanthanide complexes can be employed as luminescent probes. SDSU has produced a lanthanide ion complex coordinated by one or more organic liquids and methods for using the lanthanide complexes in lanthanide-based binding assays. The lanthanide complexes are characterized by excitation wavelengths in the visible region of the electromagnetic spectrum, emission wavelengths in the near infrared (NIR) and/or visible regions of the electromagnetic spectrum, high fluorescence quantum yields and long fluorescence lifetimes. The lanthanide complexes are characterized by photophysical properties that render them well-suited for use in lanthanide-based fluorescence spectroscopy. The resulting complexes are capable of fluorescing in the near infrared region of the electromagnetic spectrum when excited with radiation in the visible region of the electromagnetic spectrum with a fluorescence quantum yield of at least 1% and a fluorescence decay lifetime of at least 20 μsec.

Advantages: At present, commercial optical probes offer imaging windows in the visible region. As a result, probe sensitivity can be compromised by strong backgrounds signals such as autofluorescence of biosubstrates in this window. This is a major barrier for optical probes needing to achieve high sensitivity. Additionally, short wavelength excitation is usually required for obtaining strong signals from those optical probes, which can cause severe photobleaching of biosubstrates. SDSU’s lanthanide ion complexes and methods of use can overcome the obstacles presented by the current art. The complexes provide very high emission efficiency to increase detection sensitivity with long wavelength light excitation to reduce photobleaching.

United States provisional patent application #61/620,777