Luminescent lanthanide labels

Fig. 12. Dual-label time-resolved fluoroimmunoassay of AFP and CEA with luminescent lanthanide labels BHHCT-...

Differentiating lanthanide-labeled particles from rhodamine-labeled particles by luminescence... 

Of particular interest to this review is the use of luminescent lanthanide (especially europium and terbium) materials as non-radioactive markers (3,5,8,10 12,16). In addition to the safety advantages over radioactive labels, lanthanide complexes remain luminescent as long as the complex remains intact, allowing repeated detection of analytes over a much longer time period than radioactive labels. 

Lanthanide label kits are commercially available and will become more and more widely used as the nature of the visibly luminescent europium (red) and terbium (green) complexes utilized is optimized. Significant growth can also be expected in the development of lanthanide labels based on neodymium and ytterbium as their luminescence in the NIR, whilst of shorter lifetimes and requiring specialist detection equipment, is at a wavelength where tissue is optimally transparent, making in vivo uses a distinct possibility. 

Lamture, J. B. Wensel, T. G. A novel reagent for labeling macromolecules with intensely luminescent lanthanide complexes. Tetrahedron Lett. 1993, 34, 4141—4144. 

Principle of time-resolved luminescence measurement using lanthanide labels 190... 

The idea of the use of luminescent lanthanide chelates in bioanalysis can be traced back to the 1980s, when Hemmila (1985) reported a time-resolved fluorometric system using an Eu labeling reagent, which was commercially produced by Wallac Oy company. The system was intended for immunoassay and included the spectrometer for time-resolved measurements. The basic principle of the immunoassay system (DELFIA ) is shown in fig. 1. 

Weibel N, Charbonniere LJ, Guardigli M, Roda A, Ziessel R. Engineering of highly luminescent lanthanide tags suitable for protein labeling and time resolved luminescence imaging. J Am Chem Soc 2(X)4 126 4888-96. 

These systems are promising as potential labels due to high emission quantum yields and excited-state lifetimes that can be as long as several tenths of a millisecond (108). A cyclen (12-ane-N4) unit connected to a phenanthridine moiety in fluorophore-spacer-receptor conhguration (Fig. 26) exhibit strong Tb(III) based luminescence (109) in the absence of protons and oxygen. Few other luminescent lanthanide complexes are available in the literature (110,... 

Mikola H, Takalo H, and Hemmila I. (1995) Synthesis and Properties of luminescent lanthanide chelate labels and labelled antigens for homogeneous immunoassays. Bioconj. Chem. 6 (3) 235-241. 

It is important to note that, to increase signal intensity, multiple lanthanide labeling of even small molecules is possible because lanthanide luminescence, in contrast to organic dye fluorescence, [15] does not undergo cmicentratimi quenching. This can be attributed to the lack of overlap between the absorption and excitation spectra due to the large Stokes shift. 

Son A, Nichkova M, Dosev D et al (2008) Luminescent lanthanide nanoparticles as labels in DNA microarrays for quantification of methyl tertiary butyl ether degrading bacteria. J Nanosci Nanotechnol 8 2463-2467... 

Fig. 3 Two examples of NIR luminescent lanthanide complexes. Left. Nd complexes with reduced non-radiative deactivation due to replacement of C-H by C-F oscillators [13], Right. Yb(FxITC), an NIR luminescent label for the labelling of biological molecules [27]...

Luminescent Labels Based on Near-Infrared Luminescent Lanthanide Ions... 

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