A Eu(III)-macrocycle-mono-isothiocyanate, Quantum Dye, has been synthesized that has minimal contamination with the Eu(III)-macrocycle-di-isothiocyanate, which cross-links proteins. The mono-isothiocyanate has been conjugated to streptavidin (EuMac-Strept). An indirect assay with EuMac-Strept and biotinylated anti5BrdU has been used to observe apoptotic cells. This system and cells directly labeled with the Eu(III)-macrocycle-di-isothiocyanate have been employed in fading studies and reagent stability tests. The fading of cells mounted in a plastic medium was much slower than that observed when the cells were in the aqueous, micellar Lanthanide Enhanced Luminescence (LEL) solution. The fading was not the result of the photo-destruction of the Eu(III)-macrocycle, since the luminescence returned after a second addition of the LEL solution. A time-gated, peltier cooled, monochrome CCD camera has been combined with a flashlamp to eliminate imaging of the emission of fluorescein while maintaining the images of EuMAc staining. This was demonstrated with both separate preparations of fluorescein and EuMac stained cells and mixtures thereof. Time-gating was employed to produce an EuMac image of cells that were stained with both the EuMac and DAPI.

Date Published: 19 June 2003
PDF: 13 pages
Proc. SPIE 4962, Manipulation and Analysis of Biomolecules, Cells, and Tissues, (19 June 2003); doi: 10.1117/12.486324

Published in SPIE Proceedings Vol. 4962:
Manipulation and Analysis of Biomolecules, Cells, and Tissues
Dan V. Nicolau; Joerg Enderlein; Robert C. Leif; Daniel L. Farkas, Editor(s)