Lanthanide-Labeled DNA

Abstract

Lanthanide ions can have highly unusual emission characteristics in aqueous solution, including a long (millisecond) excited-state lifetime, sharply spiked emission spectra (<10 nm width), and a large Stokes shift (>150 nm). These characteristics, when using pulsed excitation in combination with time-delayed and wavelength-filtered detection, are advantageous for discriminating against background fluorescence, which tends to be short lived (primarily nanosecond) and broadly spread in wavelength. For this reason, lanthanide ions are of significant interest as alternatives to conventional fluorophores, particularly when autofluorescence is a problem. This is particularly true in high-throughput screening assays for drug development where autofluorescence commonly limits sensitivity with conventional probes and radioactivity has undesirable environmental, health, and cost considerations. Detection sensitivity of M can be achieved with lanthanides, exceeding sensitivity achievable with conventional fluorophores and approaching or equalling radioactivity. A number of companies have commercially available lanthanide-based assays although availability of the chelates remains an issue for many university researchers.A second area of practical and fundamental interest is the use of lanthanide ions as donors in resonance energy transfer studies for the detection of binding between biomolecules or the measurement of nanometer-scale distances within and between biomolecules. It has recently been realized that lanthanide ions make excellent donors in energy transfer experiments, enabling distances up to 100 Å feasible with greatly improved accuracy compared to conventional fluorescent probes. Lanthanide-based resonance energy transfer (LRET) has been applied in both basic and applied studies, including DNA and DNA-protein complexes. Very recently, it has been realized that LRET can lead to new classes of DNA-dyes with tuneable excited-state lifetimes in the 10-500 msec time regime and tunable color

Fluorescence Quenching of the Europium Tetracycline Hydrogen Peroxide Complex by Copper (II) and other Metal Ions

“…[3][4][5][6][7][8] Functionalized lanthanide complexes are also used as labels for DNA and proteins and are applicable as donors in assays based on time-resolved resonance energy transfer (RET). [9][10][11] Time-resolved measurements enable the suppression of fluorescent background signals (noise) by collecting the emitted fluorescence signal within time gates in the microsecond range, whereas the autofluorescence of other biological species decays in the nanosecond range.…”

Carbostyril Derivatives as Antenna Molecules for Luminescent Lanthanide Chelates

“…Carbostyril (cs124, 7-amino-4-methyl-2(1 H )-quinolinone) and its derivatives have been used as antenna molecules to absorb light and to transfer excitation energy to lanthanide ions, which significantly increases the fluorescence efficiency of lanthanides ( − ). To achieve this energy transfer, cs124 or its derivatives are attached to a chelate backbone (such as diethylenetriaminepentaacetic acid, DTPA), which is the site that ligates lanthanide ions.…”

High brightness red emitting polymer beads for immunoassays: Comparison between trifluoroacetylacetonates of Europium

“…Power and success of the rare earth complexes in photonics are obviously associated with the underlying, unique luminescence mechanisms. They have been analyzed and described extensively in the literature ( de Sá et al, 2000 ; Selvin and Lakowicz, 2003 ; Binnemans, 2005 ; Bünzli et al, 2011 ; Bünzli, 2016 ) and shall be summarized only briefly here: Excitation of, e.g., Eu 3+ and Tb 3+ via (intrashell) f-f transitions is possible but very inefficient due to their quantum mechanically forbidden nature. One attractive workaround is the use of rare earth complexes, in which a strongly absorbing ligand is attached to the central ion and acts as an antenna.…”